On Seas Contested

Naval intelligence dramatically improved with the capture of German Enigma codes from a German weather-reporting trawler and a U-boat. These coups enabled Bletchley Park to decipher and translate signals before forwarding them to the Naval Intelligence Division. In some cases, information reached the OIC within minutes. OIC would assess the intelligence and, after taking precautions to protect the source, pass it on to the operational units concerned.

It was the wartime DNI, Rear Admiral John Godfrey, who initiated the Inter-Service Topographical Department, bringing together experts from all three services to collect, collate and analyze information about ports, coastlines, communications and other matters in enemy-occupied territory so that this was available for invading forces. NID also included a section designated 17M which supplied naval information to the Germans through a network of controlled double-agents.

B. Doctrine
1. Surface warfare
In many ways, the Royal Navy expected the Second World War to follow the pattern of the First. Given the size of the German surface fleet, a major fleet battle such as Jutland was not expected. On the other hand, a major fleet action was expected in the Mediterranean with the Italian Navy, which had sufficient battleships and cruisers to match the combined British Mediterranean Fleet and French Mediterranean Squadron.

British doctrine was to concentrate fire as closely as possible on the target, usually firing salvoes but sometimes firing broadsides, in the belief that, if accuracy was spot on, serious, even fatal, damage could be done to an opponents. A high rate of fire was also encouraged, and this could be twice the rate of Italian ships, for example.

2. Aviation
The Royal Navy had taken an interest in aviation as early as 1910, and the Royal Naval Air Service played an important role during the First World War. This was almost a “service within a service” and at one time was given responsibility for the air defense of Great Britain, which may have contributed to its undoing as overlap as duplication of duties with the the British Army’s Royal Flying Corps led to the formation of an autonomous Royal Air Force on 1 April 1918. The new service inherited 2,500 aircraft and 55,000 officers and men from the Royal Navy.

The decision was one of those taken without benefit of hindsight. Aircrew and maintainers aboard the aircraft carriers, and seaplane carriers or tenders, all became members of the Royal Air Force, co-existing alongside the general service officers and ratings that formed the ships’ companies of the carriers. The main exceptions to this arrangement were those concerned with the operation of seaplanes and flying boats operated from battleships and cruisers, who remained naval aviators, as did a small number sprinkled through the fighter and bomber squadrons. The aircraft embarked in battleships and cruisers provided the reconnaissance and spotter role for the fleet’s guns. Aboard the carriers, however, there was a demarcation line between the seafarers and the aviators. This was emphasized to a great extent by the system under which RAF stations in the Mediterranean and Far East included flights that could operate from aircraft carriers visiting those areas. In practical terms, units were under Admiralty control afloat, and Air Ministry control while ashore.

Following the recommendations of the Balfour Committee of 1923, which examined Royal Navy and Royal Air Force co-operation, the Fleet Air Arm of the Royal Air Force was formed, with five squadrons belonging to what was then known as RAF Coastal Area, which became Coastal Command in 1936. In 1937, it was proposed that the Fleet Air Arm be handed over to full Admiralty control. Nevertheless, the Admiralty did not formally take control until 24 May 1939. In between, in 1938, the Admiralty was authorized by Parliament to implement a 300 percent increase in Fleet Air Arm personnel. While most of the RAF personnel serving with the Fleet Air Arm were to return to other postings within the service, around fifteen hundred transferred to the Royal Navy. While the RAF has been criticized for shortchanging the RN’s requirements under the pressures of building up its own strength to meet wartime needs, its systems were under considerable stress. One innovation introduced by the RAF that survived the handover was the squadron numbering system, which can be described briefly as being in the 7XX series for non-combatant and support squadrons, and the 8XX series for combat squadrons.

The authority for expansion made the Royal Navy seem finally to be equipping its air arm for war. The reality, though, was different, with few naval aviators and maintenance personnel, and hardly any naval air stations. There were no high-performance naval aircraft. The Fairey Swordfish biplane would be the offensive mainstay of the fleet, and two aircraft provided defense, the monoplane Blackburn Roc and the biplane Gloster Sea Gladiator. The RAF has been criticized for neglecting the needs of naval aviation between the wars, but these were periods of acute financial stringency for all of the armed forces. While attention normally centers on the obsolescence Royal Navy aircraft, the real problem was that an entire generation of senior officers with aviation experience had been lost with the transfer of so many to the RAF, and so even many naval officers believed that high-performance aircraft could not operate from ships.

In home waters, the Fleet Air Arm’s shore-based aircraft provided cover for convoys from the beginning of the war in Europe on 3 September 1939, until German surrender on 8 May 1945. At times shore-based Fleet Air Arm squadrons were placed under RAF Coastal Command control to ensure better integration. The FAA complemented the work of the RAF, with the latter using larger twin-engined and four-engined long-range aircraft, while the FAA operated over shorter ranges, all that was necessary for the North Sea and English Channel.

The Fleet Air Arm started the Second World War with 232 aircraft and 360 qualified pilots, with another 332 under training.⁴ The Royal Navy had seven aircraft carriers, of which four - Argus, Eagle, Furious and Hermes - were officially due to retire but remained in service as the war clouds gathered. This meant that, with the first of the Illustrious-class carriers still incomplete, the best ships were the converted battlecruisers, Courageous and Glorious, and the new Ark Royal. Not one of these three ships survived the first two years of war. There was also the seaplane carrier, Pegasus, mainly used for training aircrew for the catapult flights aboard cruisers and battleships.

There were few Royal Naval Air Stations at the outset. HMS Daedalus at Lee-on-Solent, on the Hampshire coast opposite the Isle of Wight was one of them. Not only was “Lee” convenient for the ships of the fleet based at Portsmouth, it also had a slipway for seaplanes and amphibians. Yeovilton was under construction. The Fleet Air Arm also had lodging facilities at RAF bases.
THERE IS LITTLE DISCUSSION OF DOCTRINE HERE.
3. Antisubmarine
British anti-submarine warfare was based on two concepts, the formation of merchant shipping into convoys and conducting sweeps of the open seas for German U-boats. The latter method saw the loss of the aircraft carrier Courageous on 17 September 1939 and was soon dropped as being too costly and--being a case of searching for a needle in a haystack--unproductive

Determined attempts were also made to destroy the U-boats before they could reach the open sea. The Royal Air Force sent its Bomber Command aircraft on mine-dropping missions, known as “Gardening Operations,” and attacked U-boat yards, but was hampered at the beginning of the war by the lack of a true long-range heavy bomber. After the fall of France, the Germans built U-boat pens on the French coast that were impregnable until subjected to 12,000-lbs “Tall Boy” and then 22,000-lb “Grand Slam” bombs.

Convoys were a joint venture between RAF Coastal Command and the Royal Navy. The Royal Navy and Commonwealth navies, as well as “free” forces under RN command, accounted for 514 of the 785 German U-boats sunk, with another 166 credited to the USN and twelve shared between the RN and USN. RAF Coastal Command accounted for the remaining ninety-three.

British escort vessels were fitted with asdic and this enabled the ships to home onto a submarine before dropping depth charges. Depth charges remained a standard system throughout the war, eventually supplemented by the ahead-throwing weapons “Squid” and “Hedgehog.”

Swordfish biplanes on ASW patrols were eventually fitted with ASV, air-to-surface-vessel radar, able to pick up a submarine periscope in good conditions, or the US-built equivalent, ASH. Eventually, maritime-reconnaissance aircraft also received radar. Aircraft maintaining patrols around a convoy would often direct escort vessels towards the submarine, largely because the aircraft escorting the convoy would be limited to just four depth charges each because of the weight and the limited number of strong points. The standard aerial depth charge weighed 250 lbs.

Because many U-boats were either caught on the surface or their commanders decided to fight the ancient Swordfish biplane, many Swordfish were later fitted with rocket projectiles, mounted four under each lower wing. A single rocket projectile was sufficient to destroy a U-boat, with the pilot diving towards the target at around 20 degrees.

4. Submarine
The Admiralty decided in 1939 that the priority target for the Royal Navy’s submarines would be enemy warships. The tactics used were to wait within their individual patrol areas, submerged, for enemy warships to appear. Later, in 1941 in the Mediterranean, they were frequently given roving commissions to attack anything that appeared a worthy target. The same approach was later applied in Asian waters.

The Royal Navy did not neglect specialized craft, including the midget submarine. After experimenting with a one-man submarine based design, British midget submarines evolved into the X-craft with a four-man crew. One or two crewmembers had to leave the craft in wet suits and with breathing apparatus to place explosive charges on the target. The X-craft’s finest hour came on 20 September 1943, when a small force of six vessels penetrated the defenses around the Altenfjord and placed explosive charges on the hull of the German battleship Tirpitz, putting her out of action for seven months.

As Germany had little in the way of overseas trade, other than the convoys bringing Swedish iron ore down the coast of Norway when the more direct route via the Gulf of Bothnia, froze in winter, the main theater in which the Royal Navy’s submarines operated was in the Mediterranean. The Admiralty had identified Malta prewar as an ideal base for submarines and light forces. Indeed, submarines helped keep Malta in the war by bringing in supplies at a time when convoys could not get through. The Porpoise-class minelayers were especially effective in this role, with plenty of storage room in the mine stowage tunnel and between the casing and the pressure hull, while sometimes one of the batteries would be removed to provide extra space. Rorqual on one occasion carried twenty-four personnel, 147 bags of mail, two tons of medical stores, sixty-two tons of aviation spirit, and forty-five tons of kerosene.

All in all, British submarines sank 169 warships, including 35 U-boats, and 493 merchant vessels throughout the war years, but this came at an extremely high cost, with no less than 74 British submarines sunk, a third of the total number deployed during the war. While just one submarine was lost in the four months of war in 1939, the losses grew to 24 submarines in 1940, and were almost as high again in 1942 when 20 boats were lost. A third of all losses resulted from enemy minefields.

5. Amphibious Operations
The Royal Navy had mixed success with amphibious operations during the First World War, and the doctrine that would drive the Royal Navy’s successes during the second war had just begun development as war broke out. . As early as 1923, the Admiralty had received the recommendations of the Madden Committee, including the suggestion that the Royal Marines provide an amphibious striking force and a mobile force for defending overseas bases. Initially ignored, these recommendations would form the foundation of the Royal Marine Commandos after war broke out. However, only when Churchill came to power was the importance of combined operations stressed, and in July 1940 he set a special directorate to develop the specialized training and equipment required for successful amphibious operations. Fortunately, Admiralty control of the Royal Marines made the task easier,

British and Domininon forces conducted two major raids on German bases in occupied territory. The first of these was at St Nazaire on the night of 27/28 March 1942, to destroy the dry dock, which was the only one on the Biscay Coast capable of accommodating the German battleship Tirpitz. The operation was successful, but bloody, with 144 men killed and 288 captured. On the other hand, the Germans detected the assault on the beaches and the harbor at Dieppe, on 19 August 1942, and this operation, in part a rehearsal for an invasion of France, was a failure, with many of the mostly Canadian troops taken prisoner.

The first pure British amphibious assault of the war, was Operation Ironclad, the invasion of French Madagascar. On 5 May 1942, British forces landed at Diego Suarez, taking the French by surprise and capturing their objective. Just over thirty ships were involved, including two aircraft carriers and the battleship Ramillies.

All the invasions that followed were joint Allied ventures. Their success was helped by the advent of landing craft able to land men and vehicles, even tanks, efficiently on beaches, while specialized versions were used to suppress enemy defenses with intense rocket fire. Far larger were the landing ships, and as naval technology developed, these even extended to the landing ship dock, with a floodable stern from which landing craft could be launched.

As the war progressed the British, conducted or participated in a series of large scale assaults against objectives in North Africa, Sicily, Italy, Southern France, Normandy, and Burma. After the Dieppe fiasco every operation succeeded.
6. Trade Protection
Convoys required protection across the North Atlantic or south across the Bay of Biscay to Gibraltar, where they often divided, with one convoy heading for the Cape of Good Hope and the other into the Mediterranean. There were also convoys in the Indian Ocean and up the Red Sea, and, after Germany invaded the Soviet Union, to Archangel and Murmansk with Iceland often serving as a convenient mustering point.

While convoys were not compulsory, only the fastest ships, such as the large ocean liners Queen Mary and Queen Elizabeth, could cross the Atlantic safely on their own. The fall of France gave the Germans valuable bases on the Atlantic so that their surface ships and the growing number of U-boats no longer had to sail around the north of Scotland to reach their operational areas, while the German conquest of Norway meant that air and submarine attack was a constant hazard for convoys going to and from the Soviet Union. The British Government had banned British merchant ships from the Mediterranean even before Italy entered the war, and by 1941 the situation was so desperate that supplying the beleaguered island of Malta became all but impossible. British forces in North Africa were supplied by the roundabout means of convoys sailing south to the Cape of Good Hope, and then north through the Indian Ocean, Red Sea and Suez Canal until they reached Egypt’s Mediterranean ports.

The considerable threat posed by Germany’s surface ships kept the Royal Navy’s Home Fleet heavily occupied, especially in the war’s first two years while the danger to coastal convoys presented by German motor torpedo boats remained active for the entire war.

To fill the need for mass-producible escorts, the Flower-class corvette was introduced, and later the frigate was reinvented for convoy duty. Escort forces got a boost by the exchange of old US destroyers for the use of British bases in the Caribbean.

Fighter protection against German aircraft was another problem. As a stopgap, the naval FCS (fighter catapult ships) and mercantile CAM ships (catapult-armed merchant) went into service carrying a single modified Hawker Hurricane or Fairey Fulmar - a one-shot answer, as the fighter could launch only once, leaving the pilot to hunt for a land base or bale out and hope for rescue. A better solution, MAC ships (merchant aircraft carriers operated by merchant personnel) were grain carriers and oil tankers converted with a short flight deck suitable for three or four anti-submarine Fairey Swordfish biplanes. The grain carriers, with a rudimentary hangar, could accommodate four aircraft, while the tankers had no hangar and could carry just three. These ships sufficed on the North Atlantic but did not carry enough aircraft for the Arctic convoys or those to the Cape. Fortunately escort carriers began to appear in large numbers by 1943. The Royal Navy had a small number of British-converted ships, but most were supplied from the United States, becoming the RN’s Ameer, Attacker and Avenger classes. Escort carriers could operate anywhere, though in the Mediterranean, even fast and heavily armored fleet carriers were vulnerable.

Other steps were also taken to improve the security of merchant vessels, so that by March 1941, the Admiralty Defensively Equipped Merchant Ship (DEMS) organization had equipped 3,434 ships with anti-submarine guns and had also put one or more close-range anti-aircraft guns for 4,431 British and Allied ships. Initially, naval ratings and army gunners were seconded, but later merchant seamen were trained to take their place.

The statistics for Second World War convoys were impressive. During the war years there were 2,889 escorted trade convoys to and from the UK, with a total of 85,775 ships. There were in addition another 7,944 coastal convoys, comprising 175,608 ships.⁵ It should also be remembered that since the same ship would, while it survived, take part in many convoys, the chances of a ship surviving the war were much less than these figures might suggest.
7. Communications
As an operational headquarters, the Admiralty maintained firm control of most naval operations, with the exceptional of the submariners, and not only communicated with the naval commander-in-chief, but also with individual ships. Operational commanders varied in their use of communications. Admiral Tom Phillips, in command of the new battleship Prince of Wales and the elderly battlecruiser Repulse, planned to attack the Japanese invasion fleet off Malaya, but has been criticized for maintaining strict radio silence, making it impossible for Royal Air Force units based ashore to provide air cover. On 10 December 1941, his two capital ships fell victim to Japanese aircraft. By contrast, during the Battle of the North Cape on 26 December 1943, Admiral Sir Bruce Fraser decided that good communication outweighed the benefits of radio silence, and consequently his well deployed forces succeeded in sinking the German battlecruiser Scharnhorst.

The Royal Navy adopted the Allied TBS (Talk Between Ships) radio system, but shipboard signals staffs were trained in Morse code using Aldis lamps or flags.

III. Materiel
A. Ships (includes OoB)
The Royal Navy in 1939 had twelve battleships and battlecruisers, seven aircraft carriers, of which four were either in reserve or earmarked for early retirement, a seaplane carrier, fifty-eight cruisers, a hundred destroyers, 101 other escort vessels, thirty-eight submarines, and 232 aircraft. By 1945, this fleet was to grow to 61 battleships and cruisers; 59 aircraft carriers; 846 destroyers, frigates and corvettes; 729 minesweepers; 131 submarines; 1,000 minor vessels and landing craft; and 3,700 aircraft. This was despite losing three battleships, two battlecruisers, five aircraft carriers, three escort carriers, 28 cruisers, 132 destroyers, 74 submarines, a monitor, ten sloops, three cutters, ten frigates, 22 corvettes, 32 fleet minesweepers, three fast minelayers and five other minelayers, 15 armed merchant cruisers, five AA ships, 15 fighter catapult ships, and two depot ships.

The battleships included the First World War veterans of the Queen Elizabeth class (36,450 tons full load and carrying eight 15-in guns), of which only one, Warspite, had been completely modernized before the outbreak of war in Europe, while Queen Elizabeth and Valiant were in the process of being modernized. The remaining two ships of the class, Malaya and Barham, had been only partly modernized. The smaller size of Royal Sovereign-class ships (29,150 tons full load, eight 15-in guns) complicated modernization plans, and although their AA defenses were up-dated, none of them enjoyed a major reconstruction. Later, Royal Sovereign was transferred to the USSR. Completed in 1927, Nelson and Rodney (33,900 tons full load, nine 16-in guns) had a broadside of 18,432 lbs compared with the 15,360 lbs of a more conventional eight 15-in gun ship. The most modern battleships, the King George V class (35,000 ton full load, ten 14-in guns), entered service during the war years. One remaining ship, Vanguard (51,420 tons full load), marked a return to eight 15-in guns but was not completed until the end of the war. At one stage consideration was given to completing her as an aircraft carrier, but this was finally rejected in mid-July 1942.

There were also three battlecruisers. Hood, completed in 1920 and for many years the world’s largest warship, had eight 15-in guns. The other two ships, Renown and Repulse, dated from 1916 but had been modernized between the wars; both displaced 32,000 tons and had six 15-in guns.

Aircraft carriers included the converted Courageous-class battlecruisers: Furious (converted in stages starting in 1917), Courageous (1928), and Glorious (1930). All displaced around 22,500 tons, although the two later ships could carry up to forty-eight aircraft compared with thirty-three on Furious. Elderly Argus (16,500 tons), already obsolete and due to be scrapped when war broke out, was hulked as an accommodation ship before the end of the war; in 1941 she could accommodate just fifteen aircraft. Another ship that was showing her age was the converted battleship Eagle (27,500 tons full load) which could carry just twenty-two aircraft by 1942, the year that she was sunk. The first carrier to be designed as such from the keel upwards was the small Hermes (13,700 tons), able to carry just twelve aircraft by 1939.

The most modern aircraft carrier in the Royal Navy on 3 September 1939 was Ark Royal, displacing 27,720 tons and intended to carry up to sixty aircraft in her two hangar decks, but by 1941 this was reduced to fifty-four. Planned to replace the oldest of the carriers, the new Illustrious class (28,619 tons, up to fifty-four aircraft) were fast and heavily armored; Illustrious and Formidable were completed in 1940, and Victorious in 1941. These were followed by the modified Illustrious-class Indomitable (29,730 tons, fifty-six aircraft on two hangar decks). Finally in 1944, came the Implacable class of two ships (32,110 tons, eighty-one aircraft, two hangar decks). The previous year had seen a maintenance and support carrier, HMS Unicorn (20,300 tons, up to thirty-six aircraft), join the fleet, and she performed operationally on several occasions.

By this time, the Royal Navy had started to introduce escort carriers. The first of these, Audacity (11,000 tons, just eight aircraft), was converted from a German cargo ship in 1941. She was followed in 1942 by a British ship, Activity, which was larger at 14,529 tons, but still able to carry only ten aircraft.

US-built escort carriers started to arrive in 1941 with the Archer (12,860 tons, twelve aircraft. Three ships of the Avenger class (15,700 tons, fifteen aircraft) arrived in 1942 with a fourth retained by the USN for training RN carrier pilots in the USA. Then came the Attacker class (14,400 tons, twenty aircraft), similar to the USN’s Bogue class. The 1943-44 Ameer class (15,400 tons, twenty aircraft) resembled the Bogue class, but purpose-built rather than conversions.

The Royal Navy obtained further escort carriers from British sources, largely because the Admiralty believed, incorrectly, that the welded hulls of US-supplied vessels would not be suitable for Arctic waters. The first of these were Vindex and Nairana of 1943 (around 16,980 tons, twenty-one aircraft) which were based on a refrigerated cargo ship design. The largest escort carrier operated by the RN, Pretoria Castle (23,450 tons, twenty-one aircraft), was converted in 1944 from an armed merchant cruiser and used solely for trials and training. Campania (15,970 tons, twenty-one aircraft), similar to Nairana, also joined the fleet in 1944. She was the first British escort carrier with an Action Information Organization (AIO).

Escort carriers displayed their worth during the war years, but also their limitations. The fleet needed a capable aircraft carrier but could be built to merchant shipping standards in yards with no experience of warship construction. Thus was born the Colossus class (18,040 tons full load, forty-two aircraft), known to the Royal Navy as a light fleet carrier. Five commissioned before the end of the war but reached the Far East too late to see active service.

The oldest heavy cruisers in service at the outbreak of war were the Kent class built in 1927-28, armed with eight 8-in guns and displacing 10,000 tons to comply with the Washington Treaty limits. A slightly modified London class commissioned in 1929. The Norfolk class of 1930 again was similar. These ships, known collectively as the “County” classes, were easily identified by a three-smokestack design. The York class of, 8,300 tons with just six 8-in guns and two smokestacks followed in 1930-31.

Light cruisers included the Leander class of 1933-35 (7,000 tons, eight 6-in guns, eight torpedo tubes). RN’s requirement to have fifty cruisers by the end of 1936 meant a reduction in the next class, the Arethusa class (5,220 tons, six 6-in guns, six torpedo tubes), and the small-cruiser concept recurred in two Dido classes (5,600 tons, ten 5.25-in HA/LA guns, six torpedo tubes). Manufacturing shortfalls left some ships with only ten guns or an alternate 4.5-in battery.

The need to match powerful 6-in cruisers in other navies led to the “Town” classes - the Southampton class (9,100-9,400 tons, twelve 6-in guns, six torpedo tubes) and the Edinburgh class (10,000 tons, twelve 6-in guns, six torpedo tubes). The Fiji class attempted a similar armament on 8,500 tons, though some ships had a 6-in triple turret removed. Nine guns became standard on the similar Uganda and Swiftsure classes.

These ships were augmented by a number of older ships, of which the most modern was the E-class (7,500 tons, seven 6-in guns, sixteen torpedo tubes). Three surviving members of the Raleigh class dated from 1914-1916, and had undergone considerable modification over the years, with one retaining a 7.5-in armament and another being used for training, but in 1939 these generally had six 6-in guns. The “C”classes (4,180-4,290 tons, five 6-in guns, eight torpedo tubes in some) also dated from the First World War. Several underwent conversion to an anti-aircraft role armed with ten 4-in HA guns. It had also been decided to convert the 1918-22 “D” class (4,850 tons six 6-in guns, twelve torpedo tubes) to anti-aircraft cruisers, but only Delhi made the switch, armed with American 5-in guns.

The Royal Navy utilized fifty-six merchant vessels as armed merchant cruisers, most of which retained their “civilian” names. These varied enormously in size, speed and armament, but were usually armed with obsolete 6-in guns that had been recovered from ships being scrapped. Unlike the German armed merchant cruisers which were surface raiders, the British ships were intended to act as convoy escorts but were no match for real warships as demonstrated on 23 November 1939 when the former P&O liner Rawalpindi was sunk by the battlecruisers Scharhorst and Gneisenau off Iceland, and on 5 November 1940 when the heavy cruiser Admiral Scheer.sank Jervis Bay.

British destroyers included the First World War, “V” and “W” classes, but almost every year between the wars saw seven to nine new destroyers completed. In most cases, there were two types of ship in each class, with one or two being built as destroyer-leaders, sometimes being larger but in other cases having a turret removed to provide room for the flotilla commander’s staff. Destroyer sizes, which had grown during the First World War, continued to grow between the wars, so that the “V” and “W” classes displaced 1,120 tons, while the “Tribal” class of 1938-39 were of 1,870 tons. Armament also changed. All destroyers had 21-in torpedo tubes, but most laid down during the First World War had 4-in guns while some had the 4.7-in caliber that would become standard between the wars. Wartime circumstances forced some new ships to revert to 4-in guns in HA mounts, and 4.5-in guns made an appearance late in the war. From the “B” class of 1931 onwards, all ships mounted asdic. At the time, the British shipbuilding industry had a considerable export market, and on the outbreak of war, the Royal Navy seized a batch of “H” class destroyers building for Brazil along with a pair of “I” class ships intended for Turkey. Fifty ex-USN First World War destroyers were received as the “Town” class; of these, fifteen eventually went to the Royal Canadian Navy, five spent time with Norwegian crews, and nine passed on to Soviet custody. For RN service, the ships were modified, with deeper bilge keels and ballasting to improve sea-keeping.

World War I had shown the value of the “Flower” class minesweeping sloops in a variety of tasks, especially escort duties. Post-war, no new sloops were constructed until 1927, when two were ordered incorporating improvements, and small numbers were also ordered in the years that followed, continuing the tradition of being equipped for minesweeping. In 1931, renewed interest in sloops saw the decision to build two new classes: the simple and cheap Halcyon minesweeping class, and the improved Grimsby escort class still capable of minesweeping and equipped for duty in the tropics. Under wartime conditions, even the Halcyons operated mostly as escorts, while minesweeping needs were met by a combination of new construction and converted fishing vessels.

Soon after, a coastal sloop was also designed primarily for ASW, displacing 742 tons with a speed of 20 knots and a range of 4,050 miles; the Kingfisher class and the improved Guillemot class, later re-classified as corvettes, were built between 1934 and 1939. At the same time, planning began on a new sloop to be known as the Ocean Convoy, without minesweeping gear but with increased armament and anti-submarine abilities. This was a larger vessel than any before, at 1,520 tons, with almost 19 knots maximum speed and a useful endurance of 6,400 miles. Construction began with the Bittern class of 1935-38 and continued with refinements in the Egret, Black Swan, and Sutlej classes, extending to war’s end with the Modified Black Swan class. As the war progressed, these ships changed from being riveted to having as much as 30 percent of the structure welded, while stabilizers were fitted to both the Black Swan and Modified Black Swan classes. Under Lend-Lease, ten USCG cutters were also transferred to the Royal Navy.

The Royal Navy eventually commissioned about 3,500 trawlers, whalers, drifters, and fishing vessels to perform miscellaneous duties including local patrol and minesweeping, but these were not suitable for anti-submarine work. Something faster was needed, ships that would cope better with constant patrolling on the high seas than destroyers. Four classes were selected: the “Flower” class corvettes (1,170 tons), the “Castle” class corvettes (1,580 tons), the “River” class frigates (1,855 tons), and the “Loch” class frigates (2,260 tons, the “Bay” class being a related design with AA emphasis). The “Captain” class frigates were supplied under Lend-Lease from the USN which rated them as “destroyer escorts” (Evarts and Buckley classes). Britain’s own “escort destroyers” of the “Hunt” classes (1,314-1,515 tons), while intended as escorts, more nearly approached destroyer capabilities.

The Royal Navy placed considerable emphasis on mine-laying and mine-countermeasures. Six large and fast minelayers of the Abdiel class commissioned between 1940 and 1943. These displaced 2,640 tons, could reach almost 40 knots, and could carry 150 mines; although equipped with 4-in guns, they were sometimes referred to as cruisers.

A few “Hunt” class minesweepers remained from World War I, and large numbers of new ships were commissioned, including the Bangor class (often pressed into escort duty) and the Algerine class (large enough for ocean escort, though not the equal of the “Flowers”). These were augmented by almost 400 motor minesweepers for coastal waters; the Americans supplied 152 others under Lend-Lease, along with 22 larger vessels known as the Catherine class.

Among the submarine fleet, some elderly boats of the “H” and “L” classes lingered after lengthy service. Apart from Graph (former German U-boat U-570 captured in August 1941), some captured Italian units, and old American boats used in training, the submarine classes during the war years included:

- “O” classes (1,831-2,038 tons submerged, 1927-30), designed for distant patrol with habitability suitable for the tropics, three series, none of which performed as expected.

- “P” class (2040 tons submerged, 8 torpedo tubes, a 4-in gun, 1930-31), successor to the “O” classes, and similarly unsuccessful.

- “R” class (2030 tons submerged, 8 torpedo tubes, a 4-in gun, 1930-32), final expression of the “O” concept.

- Thames class (2,700 tons submerged, 6 torpedo tubes, a 4-in gun, 1932-35), a larger and faster ocean patrol class, the first British submarines capable of more than 20 knots, intended to keep pace with a battle fleet.

- “S” class (935 tons submerged, six torpedo tubes, a 3-in HA or 4-in gun, a range of 4,700 miles), for work in narrow waters. An initial batch entered service in 1932-33, followed by more in 1934-38, then two more sets in wartime as the Admiral (Submarines) decided that additional submarines were required to operate in the North Sea, for which the “U” class was too small and the “T” class too big. Each series incorporated improvements in the light of experience, such as increased diving depth and noise reduction. Later versions had increased fuel provision created by using part of the ballast tanks, with operations in the Far East in mind, for which Freon air conditioning units were also specified.

- Porpoise class minelayers (2,157 tons submerged, 8 torpedo tubes, a 4-in gun, 50 mines, 1933-37). One problem was the time taken to flood the mine-casing, so that diving took longer, but with a special Q-tank fitted, diving time went from 92 secs to 74 secs, about the same as for the Odin class. These submarines also proved their worth as cargo carriers on the “Magic Carpet” runs to besieged Malta.

- “T” class (1,595 tons submerged, 8 torpedo tubes, a 4-in gun and 2 Lewis guns), commissioned in three series from 1938 onwards with the first eight operational on the outbreak of war and another eleven under construction. The type was intended to replace the “P” and “R” classes in the Far East. The increased used of welding and better steel gave the second batch improved diving depth of 350 feet with the first craft diving to 400 feet safely on trials.

- The “U” and “V” classes (700 tons submerged, 4-6 torpedo tubes, a 3-in or a 12-pounder gun), three series commissioned from 1938 onwards, initially as training submarines. Experience in the Mediterranean soon showed the need for small submarines in the clear and relatively shallow waters. Diving depth was 200 ft. Later vessels had the two bow external tubes omitted in favor of a deck gun, a modification that also improved sea-keeping. Later boats in this series had superior welded pressure hulls.

- P 611 class (856 tons submerged, 5 torpedo tubes, a 4-in gun, 1941-42), four boats built for Turkey, but the British kept two for themselves.

A final class, the “A” class, entered service too late to see action.

In all of the above, the general practice was to have torpedo re-loads on the scale of one for each internal tube. Under wartime pressures, AA armament with Oerlikon guns was introduced on all except the small “U” class. Stern firing tubes were also added in 1940 and 1941 to the “S” and “T” classes, with both having a stern tube and the “T” having two aft-facing tubes amidships. Air conditioning was gradually introduced as the dehumidifiers in the “T” and “S” classes were inadequate for tropical operations, increasingly important as the Royal Navy moved back into the Far East. Freon air-conditioning allowed patrols of up to 45 days, sometimes longer.

The Royal Navy came late to the concept of midget submarines, on which the pioneering work, as with human torpedoes, was largely conducted in Italy. After experiments with the one-man Welman which was effectively a cross between a human torpedo and submarine, the Royal Navy developed the 35-ton X-craft, which were deployed against the German battleship Tirpitz, with considerable success. There were two types, the original X series and the XE series developed for operations in the Far East. Both types had a four-man crew, one of whom had to be a diver, and carried two large explosive charges which had to be laid under the target, while the diver could also add limpet mines to the hull. The midget submarines had to be taken fairly close to the target by a mother ship, ideally a larger submarine, but in the case of the attack on Japanese shipping at Singapore, the XE-craft managed a trip of forty miles each way.

While motor torpedo boats had been used by the RN during the First World War, and though British builders exported many craft between the wars, the Admiralty placed no new orders until 1935. By 1945, five hundred motor gunboats and torpedo boats had seen service, perhaps the most famous being the Fairmile D “dog boats” with the firepower of their two 6-pounders. Fairmile also had great success with of motor launches. The dozen Fairmile A launches earned few friends but taught important lessons that led to mass-production of the B-type craft: 388 built in the UK, with another 264 in the Dominions, many of them funded locally. Another mass-production success, the Admiralty harbor defense motor launch, resulted in roughly 450 completions. In the Mediterranean, these craft also undertook open water duties, including escorting convoys off the North African coast.

B. Aviation
1. Ship-based
The outbreak of war found the Fleet Air Arm with inadequate aircraft. The Fairey Swordfish was out-dated. Its successor, the Albacore, was, amazingly enough, yet another biplane, and one with an engine so troublesome that the Swordfish soldiered on. The Gloster Sea Gladiator fighter was the last biplane fighter built for the RAF. The Fairey Fulmar fighter monoplane looked modern, but the need to carry a two-man crew made the aircraft too heavy and its performance was barely adequate to counter a bomber, much less enemy fighters. An oddity was the Blackburn Skua, officially fighter/dive-bomber-reconnaissance, but to those who had to cope with it, “more dive-bomber than fighter.” All of this was partly because of neglect of the Fleet Air Arm’s aircraft procurement needs whilst under RAF stewardship, but also partly because many senior British naval officers believed that high-performance aircraft could not operate safely from aircraft carriers.

The aircraft operated by the Fleet Air Arm during the war years included many transport types, and on communications and training duties, many of the aircraft were not unique to naval use. While the aircraft available to the Fleet Air Arm improved as the war progressed, the newcomers were not without their failings. Apart from the Albacore’s problems, the Fairey Barracuda was a maintenance nightmare, and while it did useful work in the European theatre, it was badly outclassed in the Far East and soon withdrawn. The Hawker Sea Hurricane was an interim measure, lacking folding wings. The Supermarine Seafire was too delicate for carrier work and lacked range. The Vought Corsair was a tough, fast, fighter-bomber with a good range, but its bouncy landing gear and long nose made for difficult landings.

US aircraft started with the Grumman Wildcat, initially known to the British as the Martlet until USN involvement in the war brought about a much-needed standardization of terms. It was followed by the Hellcat and the Corsair, and the Fleet Air arm at last obtained a modern bomber and torpedo-bomber with the Grumman Avenger.

Aboard the battleships, battlecruisers and cruisers, amphibians were operated. Initially these were the Supermarine Walrus, but they were later replaced by the Supermarine Sea Otter, both of them single-engined biplanes but with the Sea Otter having a tractor propeller and the engine mounted in the upper wing, while the Walrus had a pusher propeller and the engine mounted just below the upper wing. These were slow, lumbering aircraft, useful for SAR and fleet spotting, but with no combat role.

2. Shore-based
British shore-based maritime aviation was provided by the Royal Air Force’s Coastal Command, although the Fleet Air Arm’s Swordfish squadrons in particular could, and often did, come under RAF control and took part in offensive actions, often including mine-dropping off ports in Belgium and the Netherlands.

At the outbreak of war in September 1939, Coastal Command aircraft included the Avro Anson. There was also the Vickers Vildebeest biplane. Amongst more capable aircraft, a torpedo-bomber version of the Handley Page Hampden was also available, as well as some elderly flying boats. The sole aircraft capable of the duties expected of it was the Short Sunderland, a four-engined long-range maritime-reconnaissance flying-boat, capable of remaining on patrol for twelve hours or more, and heavily armed as well as being able to carry 2,000 lbs of depth charges. Anti-shipping strikes were also mounted, and these used aircraft such as the Hampden, Bristol Blenheim and later the fast Beaufighter from the same manufacturer.

As the war progressed, Vickers Wellington medium bombers provided useful service, and these were augmented by US Lend-Lease aircraft such as the Consolidated Catalina flying boat and the B-24 Liberator heavy bomber, the Boeing B-17 Flying Fortress and the Lockheed Hudson as well as the British Avro Lancaster and Vickers Warwick. ASV radar and the Leigh light enhanced efficiency. There was always strong competition between RAF Bomber Command and Coastal Command for the most capable heavy bombers, while the bomber-types in Coastal Command service were called upon to make up the numbers for the famous “Thousand Bomber Raids.”

While search and rescue was part of Coastal Command’s duties in mid-ocean, SAR in home waters was most usually carried out by a unit with RAF Fighter Command, which also deployed air-sea rescue launches.

C. Weapon systems
1. Gunnery (surface/air, includes FC and radar)
British battleships ordered or commissioned during the First World War had guns of 15-in caliber, while the 1927 vintage Rodney and Nelson, had 16-in. However, as a result of the London Naval Treaty, the most modern battleships to see war service reverted to guns of just 14-in caliber. The heaviest cruiser guns were 8-in, while most modern light cruisers had 6-in, though the Didos carried 5.25-in or even 4.5-in.

Escort vessels had varying calibers as their main armament. The older destroyers had 4-in, but 4.7-in became standard at the end of World War I. The 4-in caliber made a return in some wartime ships, compensating for its lesser hitting power by allowing much improved performance against aircraft. Some late-war destroyers introduced the 4.5-in gun, with the “Battle” class featuring HA/LA mounts. Frigates, sloops and corvettes had 4-in.

Submarines had either 4-in or 3-in guns, usually mounted singularly forward of the conning tower.

These varied calibers did not make logistics any easier, but there are no recorded instances of this affecting the outcome of a naval engagement.

Both Bofors and Oerlikon 20mm guns were fitted to most warships for anti-aircraft protection, while the larger ships also received the 2-lb multiple pom-pom, which many regarded as the best AA defense against low-flying aircraft. Further defense was provided by machine guns, especially the Lewis gun.
2. Torpedoes
The Royal Navy used torpedoes extensively, fired from submarines and dropped from aircraft, as in the successful attack against the Italian fleet at Taranto on the night of 11/12 November 1940, and also fired from destroyers and even cruisers. The Royal Navy also used motor torpedo boats in coastal waters, and given the short distance across the English Channel, no more than 22 miles at its narrowest, this also meant French and Belgian coastal waters.

Submarines generally used the 21-in Mk VIII family of torpedoes, ultimately with a 805-lb explosive and a range of 5000 yards at the maximum speed of 45.5 knots. Destroyers and cruisers mostly used a 21-in Mk IX (805-lb explosive, of 41 knots). Aircraft initially used the 18-in Mk XII (388-lb explosive, 40 knots) and later the Mk XV (545-lb explosive, 40 knots). All of these used thermal propulsion. Initially, only contact charges were used, but later magnetic fuses were introduced, but these did not always perform well.

3. ASW
Anti-submarine warfare was seen as a major part of the Royal Navy’s role in wartime, and destroyers, frigates, sloops and corvettes were all fitted with asdic. Depth charges were dropped using rails and depth charge throwers, eventually supplemented by ahead-throwing weapons like the Hedgehog and Squid.

A variety of depth charges were produced. Those used by aircraft had a pre-set depth, but shipboard charges could be set to detonate at various depths, the maximum increasing from 300 feet to 1000 feet. Depth charges would be dropped in patterns, with three rolled over the rails and two fired by throwers off the port and starboard quarters, attempting to leave a space of between 120 and 180 feet between each depth charge. A depth bracket was also possible combining lighter and quick-sinking heavier depth charges, for example, the Mk VII (about 420 lbs) and the Mk VII Heavy (about 570 lbs). Overall, 43 percent of German submarines were sunk using depth charges. One problem was that, as the hunter ran over the submarine, the asdic signal was briefly lost, allowing enough time for the target to take evasive action. Consequently forward-firing projectors proved invaluable. The Hedgehog of late 1941 fired up to 24 light projectiles but had the weakness that they only exploded on contact. The Squid, used only by the Royal Navy and introduced in 1943, was effectively a mortar firing three 390-lb projectiles which exploded at a set depth giving a triangle with sides of roughly 120 feet. A variation was the Double Squid which could fire two sets of projectiles set to explode at two different depths, which in theory raised the possibility of destroying a target to 50 percent from just 6 percent with standard depth charges, and 20 percent using Hedgehog.

4. Mines
Mines were used both offensively and defensively by the Royal Navy during the war, including laying no less than 6,000 to deny the Straits of Dover to U-boats, and the service devoted even more effort to mine countermeasures than to mine laying. The Royal Force, using both Coastal Command and Bomber Command aircraft, also made strenuous efforts to drop mines in the estuaries, harbors and even rivers and canals of enemy territory. The May 1940 effort over the Rhine succeeded in temporarily stopping most of the river traffic between Karlsruhe and Mainz.. For the nearer ports of mainland Europe, land-based RN Swordfish squadrons were often called upon to provide additional mine-dropping.

Moored contact mines, usually laid by surface vessels carried 600 lbs of high explosives and were used in coastal and harbor waters of no more than 600 ft in depth. Influence mines (either pressure, acoustic or magnetic), with around 775-lb of explosive, were usually dropped by parachute from aircraft; by early 1944, this could be done accurately using radar from as high as 15,000 feet, reducing the danger to AA fire.

By chance, the Royal Navy recovered intact a German magnetic mine in the Thames Estuary in November 1939, and by the middle of 1940 had developed a magnetic sweep. The Germans also introduced acoustic mines, detonated by the sound of a ship’s propellers or machinery, and by November 1940, the British had developed an acoustic sweep. Contact mines were swept using paravanes towed by the minesweeper to cut the mine’s mooring cable using specially weighted sharp cutters, leaving the mine free to float to the surface and be destroyed by gunfire. In addition to magnetic sweeps, warships and merchantmen alike were fitted with degaussing equipment which eliminated the magnetic field of a steel hull, while RAF Coastal Command used low-flying aircraft with circular magnetic coils.

Pressure mines were developed by both Britain and Germany, but both hesitated to use them for fear that an unexploded example might be found and its secrets revealed. When the Germans eventually employed them off Normandy, they had 400 available. Inevitably, one was found and dismantled, but no counter-measure could be developed: all the British could do was calculate the maximum speed a ship could move in different depths without detonating the mine.

D. Infrastructure
1. Logistics
The Royal Navy’s fleet train was provided by a branch of the Merchant Navy, the Royal Fleet Auxiliary, which dated from 1905. In peacetime, the Royal Navy’s supply chain was spread across the world with a network of base ports, refueling stations and depots. During the Second World War, many of these were denied to the Royal Navy which lost its two main Far East bases at Hong Kong and Singapore.

It was during the war that replenishment at sea (RAS) became well established. The German method of transferring fuel in rubber hoses was adapted after the capture of two of the German battleship Bismarck’s supply ships, with experience in Pacific operations still using the astern method but with oil pumped over through a flexible bronze hose. It was not until late in the war that the USN abeam method of fuel replenishment and the heavy jackstay method for transfer of stores were adopted.

The number of ships varied, increasing as the war progressed with purpose-built ships and others “taken up from trade,” that is requisitioned merchant ships. For the Normandy landings, these even included many converted trawlers and fuel barges. By August 1945, the RFA totaled ninety-two ships.
2. Bases