Air Power over the Atlantic- Part 1


My first post wherein I will attempt to be more original in my thoughts and also properly quote the work of others. I appreciate the continued support of this series, and to be honest I think I will enjoy getting to exercise my own ideas on the matter.


“The Far Distant Ships” by Joseph Schull, ISBN-10 0773721606 (An official operational account published in 1950, somewhat sensationalist)

“North Atlantic Run” by Marc Milner, ISBN-10 0802025447 (Written in an attempt to give a more strategic view of Canada’s contribution than Joseph Schull’s work, published 1985)

“Reader’s Digest: The Canadians at War: Volumes 1 & 2” ISBN-10 0888501617 (A compilation of articles ranging from personal stories to overviews of Canadian involvement in a particular campaign. Contains excerpts from a number of more obscure Canadian books written after the war, published 1969)

“The Corvette Navy” by James B. Lamb, ISBN 0-7737-3225-X, (A shorter book that contains personal anecdotes of Mr Lamb’s service aboard corvettes during the Battle of the Atlantic, and later his involvement in the D-day landings)

“The Essential Aircraft Identification Guide: Allied Bombers 1939-1945” by Chris Chant, ISBN 978-1-905704-70-5

“The World Encyclopedia of Bombers” by Francis Crosby of the Imperial War Museum, Duxford. ISBN 10 1780192053

Pictures are courtesy of Wikimedia Commons, Library and Archives Canada,, The Rooms Provincial Photo Archive, and other sources. I only use photos that exist in the Public Domain unless otherwise stated.

Coastal Command, 1939-1940

I would take a break from our main narrative at this time to discuss air power and its effect on convoy escort and submarine hunting operations, indeed the Battle of the Atlantic in general. An aircraft was an enormous threat to any U-boat commander. The ability for expanded air power to decimate conventional warships has already been demonstrated several times in my other posts. The annihilation of ‘Force Z’ off Manila and the destruction of Bismarck both proved that even the mightiest new warships were vulnerable to air power. A tiny submarine had perhaps one of the worst possible matchups. Limited anti-aircraft armament which requires the boat to be surfaced to operate. On top of that is the limited amount of damage that the attackers have to deal to accomplish their objective. Any aircraft attack most often forced the submarine to dive, where it was at its slowest and more vulnerable to escort attack. Aircraft need only pierce the outer pressure hull with cannon fire to prevent the submarine from being able to dive, at least until the crew could affect temporary repairs, and even then diving depth would usually be limited by such damage. Another obvious advantage was reconnaissance. High-flying air patrols could spot U-boats and alert the convoy long before the first torpedoes were fired.

In short, an aircraft could destroy a U-boat or seriously damage it with potentially a single strafing run, whilst being completely immune to counter attack in most scenarios. A U-boat rendered unable to dive would be easy pickings for a future attack from other aircraft or Allied escort vessels. So it was, that new air bases and technologies would be developed alongside the burgeoning RCN to aid in the escorting of convoys and destruction of Submarines. The RN especially would develop ASW aircraft for this purpose, as would the Americans when they entered the war.

Pre-war, ordnance being mounted to aircraft for the purpose of attacking submarines had already been established. The payload carried depended on the aircraft in question, but was obviously much smaller than that of any warship. High-powered autocannons and heavy machine guns were obviously the next best weapon, but if the submarine escaped the first pass, or saw (or heard) the aircraft coming and got sufficiently underwater then the strafing runs were useless. One of the few advantages a U-boat did possess was its relatively tiny size from the air, even when fully surfaced. With decks awash and only the tower showing (the format from which U-boats often launched their night attacks) the target was even more miniscule.

The RAF branch responsible for submarine hunting was Coastal Command, not to be confused with the Fleet Air Arm, which was responsible for carrier-aircraft and other aircraft in service to the RN. Coastal Command was formed in July 1936 out of the remnants of Coastal Area Command (est. 1919) to perform the maritime duties of the RAF, after the aforementioned Fleet Air Arm became a fully RN service. It is not unfair to say that Coastal Command was the red-headed stepchild of the RAF pre-war. It was formed in haste, not given sufficient resources or long term acquisition planning, and frequently played second fiddle to RAF Fighter Command and Bomber Command, who got most of the attentions of the senior staff. Its primary objective was to protect UK maritime interests against submarines, surface warships, and aerial threats, whilst also conducting aerial attacks against enemy vessels.

As with other RAF commands, Coastal Command was structured regionally around ‘Groups’, each comprising a number of squadrons operating from bases close to the UK’s long coast. The ‘Cinderella Service’ as First Lord of the Admiralty A.V. Alexander called it, was frequently last priority for men and equipment and had to make do with what it had. The delivery of aircraft was often so limited, indeed, that many units were ‘borrowed’ from the Fleet Air Arm (FAA). The only ASW weapon they possessed besides cannon/machine-gun fire was a small bomb that had to strike a submarine to detonate, the Anti-submarine bomb. Given the aforementioned miniscule target that a submarine was from the air, and the alarming tendency of this bomb to ‘skip’ off the water like a rock and bounce back into the air, early operations might have been comical had they not been so tragic. Absolute faith in asdic had prevented further ASW weapons development, indeed, in the 8 years since its introduction into RAF service, they had not once tested it against an actual submarine.

At the outbreak of war in 1939, Coastal Command (henceforth referred to as CC) had an odd collection of underperformers and obsolete veterans in its inventory.

At their disposal were three Groups: No.15, No.16, and No.18.

  • Ten squadrons of Avro Anson ( All Groups)
  • Two squadrons of Vickers Vildebeest (No.16 Group)
  • Three squadrons of Short Sunderland flying boats (No.15 Group)
  • Three squadrons of Saro London flying boats (No.15 Group, No.18 Group)
  • One Squadron of Supermarine Stranraer flying boats (No.18 Group)
  • A limited number of Lockheed Hudson aircraft
  • One Squadron of Saro Lerwick flying boats (No. 18 Group)

Of these, only the Sunderland and Hudson would stand apart as actual worthwhile assets to Coastal Command. The London’s, Vildebeest’s and Stranraers were quite obsolete. The Anson wasn’t terrible but lacked the range required to fully patrol the North Atlantic and couldn’t carry depth charges. The Hudson had promise, with a range of 3150 Km, but was not yet available in the numbers that CC needed. The new two-engine Saro Lerwick had been introduced in April 1939 and then found to be unsuitable. This left the Sunderland, of which there were only three squadrons available.

(Avro Ansons of Coastal Command, photographed here in 1937)

(A Saro London in 1939. They were built between 1934 and 1939, and phased out quickly after seeing limited service. Some were given to the fledgeling RCAF)

The Sunderland was developed by Short Brothers for the RAF, specifically to fulfill British Air Ministry Specification R.2/33 for a long-range patrol/reconnaissance flying boat to serve with the RAF. Developed in concert with the civilian S.23 Empire flying boat, the aircraft has the look of a passenger flying boat of the era. Indeed, the Sunderlands would rescue many merchant sailors over the course of the war, having an abnormally large passenger capacity for a military aircraft. Internally the aircraft had two decks, the lower containing six bunks, a galley with two kerosene pressure stoves, a porcelain flush-toilet, an anchoring winch, and a small machine shop for in flight repairs. The crew was to be six men all told, but the large amount of space allowed the crew to go as high as 12 men depending on the mission requirements. The large amount of room also allowed for numerous additions to the aircraft’s weapon and equipment suite as the war progressed.

(“The greatest flying boat ever built”. The Short Sunderland. This is a late war example Mk V.)

The early Sunderlands possessed a maximum range of 2,848 Km (or 1,780 miles) at a cruising speed of 285 km/h, propelled by four Bristol Pegasus XVIII nine-cylinder radial engines. The large wings accommodated space for six drum-style fuel tanks. In conjunction with four smaller fuel tanks installed behind the rear wing spar, the Sunderland could conduct patrols lasting 8-14 hours. For comparison, the Anson had a range of 1271 Km, the London a range of 1770 Km, the Stranraer a range of 1609 Km, and the Vildebeest a range of 2012 Km (with drop tanks). Besides the Anson, all others were obsolete, and the Sunderlands range was more than double that of the Anson.

Armament varied throughout the war, but at the start the Sunderland had a defensive armament of four .303 machine guns in a powered turret in the tail, and two manually fired .303 machine guns each side of the fuselage just behind and below the wings. Two more guns were mounted in the nose. All of these would later be upgraded to .5-inch calibre Brownings, and more guns would be added, including four forward-firing guns fixed on either side of the nose (two on each side) fired by the pilot, and two more guns mounted in a dorsal turret on the upper fuselage. Payload was carried internally in a purpose-built bomb room. The ordnance was winched up onto racks under the centre wing structure, and then deployed out through doors beneath the wings.

(The deployed bomb-rack of a Short Sunderland.)

The Sunderland was exactly what was desirable in an ASW aircraft. Outstanding range, the ability to loiter over a convoy for a long time, heavy armament. The ability to land on the water and rescue survivors was simply an added bonus. A result of being a flying boat and having been developed in conjunction with a civilian passenger aircraft. When the British merchant vessel Kensington Court was torpedoed 70 miles off the Scillies on September 18, 1939 by U-32, two patrolling Sunderlands had the entire crew of 34 back on dry land just an hour after the ship sank. (It should be noted here that U-32 actually surfaced and fired her deck gun at Kensington Court first, allowed the crew to abandon ship, then finished the vessel off with a torpedo.)

As excellent as the Sunderland was, it could not perform the maritime duties of the RAF alone, and new aircraft were required to give CC the ability to operate 24-hours a day, as this was considered a core requirement of Coastal Command. The Anson was fine for Channel patrols but there was a shortage of Anson engines. Several delegations were dispatched by the Air Ministry to the US to see if more Hudsons could be acquired, but for the moment their delivery rate remained an abysmal two per month.

CC tried without much success to improve its capabilities in the first months of the war, but was aided by the fact that the German naval offensive in the North Atlantic was also not very substantial in the early war. Reinforcements would come from several sources. Royal Australian Air Force No.10 Squadron travelled to Britain to receive training on Sunderlands, intending to eventually bring that training home and fly them in the Pacific. The outbreak of war kept them in Britain and saw them transferred to the authority of CC. They were the first British Commonwealth squadron to see WW2 service, and sank their first U-boat on the First of July

Lack of effective armament was hampering effectiveness more so than lack of aircraft. The ASB was useless beyond belief. Even when hits were scored, the explosive did not always cause critical damage, something that might have been known had they tested it pre-war.

(A Sunderland of No.10 Squadron RAAF sets out on patrol in 1941.)

Help with coverage also came from sources closer to home. In February 1940 four squadrons were transferred from RAF Fighter Command, all equipped with Bristol Blenheims. Two more squadrons of Blenheims came from RAF Bomber Command in June 1940, and another squadron of Fairey Battles would come from the bomber service in August (they were deployed to Iceland). The Blenheim was a little better than the Anson, but still mostly obsolete. It had a maximum range of 2350 Km, which put it above everything except the Hudson and Sunderland. Payload was a maximum of 1000 lbs internally and 320 lbs externally. The Fairey Battle had a range of 1609 Km, and payload capacity of 1000 lbs. They had been thrown into the fighting in France to receive little success and appalling losses, and their transfer to CC was because they were useless to the other Commands.

CC was grateful for every aircraft it could get its hands on. Chris Chant describes the growing pressure on Coastal Command in his book Essential Aircraft Identification Guide: Allied Bombers 1939-1945

“…By the middle of 1940 the CC was faced with a host of often conflicting demands: anti-invasion patrols over the North Sea and English Channel, long-range fighter protection over the South-West approaches, surveillance of the vast length of coast controlled by the Germans, escort patrol for the convoys, and offensive patrols against enemy vessels. As the war continued, all these had to be extended in scope and range, but Coastal Command had a mere 300-500 operational aircraft. Most unfortunate of all, given the growing threat of the U-boat, was the fact that of these aircraft a mere 34 were Sunderlands…”

Italy’s entry into the war also demanded transfer of aircraft to serve in the Mediterranean and a few squadrons were transferred to Gibraltar. Squadrons would also be transferred to the African theatre as it became more important.

By the Autumn of 1940, the issue of numbers was somewhat mitigated by further squadron transfers, but this brought its own host of faults. CC was now operating 11 different aircraft types (not including trainers) and this caused serious problems with training, logistics, and conversion. Not all of these aircraft were effective in their new roles. As discussed in my other posts, the convoy routes were soon altered to the North-West Approaches, and the ports of Liverpool and Glasgow. The shift north made strategic sense, but compounded CC problems. They did not have the airfields and flying boat bases available to facilitate the transfer of large numbers of aircraft to the new theatre. U-boat commanders were also learning new tricks. The limits of air cover were more pronounced in the north, and better understood by this point in the war. U-boats began waiting until convoys were out of air cover range, and struck more and more at night, where even with aircraft on station the chances of hitting a U-boat from the air were further reduced. Bright moonlight was the only advantage aircraft had, and that was a fickle one at best.

(A Coastal Command Sunderland flying over convoy TC-6, which was carrying yet another load of Canadian Army troops to England.)

The only real hope was development of technology to assist in U-boat detection, day or night, rain or shine. Air-to-Surface Search Radar (ATSSR) was a good option, but few aircraft carried this electronic aid in the early war, and, similar to the RCN forays with radar, it was only useful against a fully surfaced U-boat at a range of less than 3 miles. Even Anti-Surface Vessel radar (ASVR) was limited. Crews still had to obtain a last minute visual confirmation of the target, and there was no way to illuminate a target at night. Even if the target was fully acquired, release of ordnance under all but perfect conditions was dangerous to the aircraft, thanks to a lack of an accurate low-altitude altimeter.

Autumn of 1940 saw Captain Ruck-Keene recommend that depth charges become the standard weapon of choice for ASW patrol . A Captain by the name of D.V. Peyton-Ward, the Naval Liaison to Coastal Command recommended that the Anti-submarine bombs be removed from service entirely, and that the depth charge become the weapon of choice for CC squadrons on convoy escort duty. The Admiralty accepted these proposals, and what seemed a rather obvious substitution was finally initiated.

Depth charges showed much more promise than ASB did. In 1939 they could only be carried by the flying boats in CC service, introduction of other hand-me-downs from RAF Bomber Command would increase capability, but that was not until RAF Bomber Command themselves received new aircraft. The 450lb naval charge was chosen by Coastal Command (no aerial charges existed, so a conversion was necessary) and was given nose and tail fairings as a safety precaution so that if the aircraft had to ditch, the charges would not explode. They were set for a detonation depth of 50 feet, but this was later found to be too deep. The 250lb charges exploded on contact, and were likely to bounce back out of the water if the target was missed (although they wouldn’t skip like the ASBs had). Over the course of the war, operational data about lethal proximity, best detonation depth, and Torpex-filled weapons would make depth charge attacks deadlier and deadlier. New tactics would also be developed, such as the “Total Release” tactic promoted by Captain Peyton-Ward, who advocated for dropping the entire payload at once to ensure a kill. In 1942 Air Chief Marshal Sir Joubert de la Ferte recommended that carrying both 500 lb and 250lb depth charges was not advantageous, and that it was better to go with one or the other when going on missions. Carrying larger numbers of smaller charges was to prove the better tactic. Depth charge development would continue onwards throughout the entire war, with the introduction of different charge sizes (a 600 lb charge was added to the inventory in 1943. It could be dropped from 5000 feet up, and developments in exploder technology would see it dropped from 12,000 to 15,000 feet, at any speed, with 80 foot spacings.)

The 250 lb mass drop would remain the most popular however, with John Slessor (GOC of CC in 1943) writing that of all the different armaments available, from ASW rockets to cannon fire to torpedoes, none could compare to the Mark XI depth charge. All of this was in the future however, and merchant vessels were being sunk now.

(250 lb depth charges being loaded into the bomb bay of a Boeing Flying Fortress IIA in May 1943.)

Despite the increase in the number of squadrons, between the beginning of June and the end of 1940, more than 3.04 million tonnes of British, Allied and neutral merchant shipping were sunk. Approximately 59% was to U-boats, 12% to the Focke-Wulf Fw 200 Condor and other aircraft, and the rest to mines and surface raiders.

Coastal Command was involved in a number of offensive operations against German surface vessels and merchant ships during this time period, but my post mostly concerns their ASW service, so I will not be mentioning these events unless they relate specifically to the Battle of the Atlantic. In the early war, convoys from Britain lacked escort once they passed beyond 13 degrees west. Hudsons had the best range out of any CC aircraft, and even they could only make it out to around 17 degrees west before they had to turn back, and their time over this area was minimal. Despite this, supreme effort was made by CC to provide cover from first to last light, the time when U-boats could use the rising and setting sun to silhouette their targets.

The fall of France gave the U-boats and Luftwaffe access to bases in France, and CC began extending patrols into the Bay of Biscay. Using french ports, U-boats extended the maximum range of their attacks out past 20 degrees west, giving yet more ocean space to hunt beyond Allied air cover. The British would respond by establishing the ACHQ (Area Combined Headquarters) for ASW operations in the Atlantic. Organisation between the services was deemed essential, and ACHQ became the nerve centre of the Atlantic war. Despite this interoperability, Coastal Command and the other Allied forces could not stop the first ‘Happy Time’ from occurring. Between May and December 1940 the Germans sank 298 ships for more than 1.6 million tons, almost all of them in the Northwest Approaches. Coastal Command needed more resources, not just aircraft, but aircraft capable of performing the task to the best of their ability. The Blenheims and other ill-suited aircraft were much like the corvettes in the RCN. They were used because they were available, not because they were particularly good at the job. Indeed, there were similarities between the two organisations. In 1939-40 Coastal Command suffered from a lack of trained personnel, and a lack of training facilities to train the fresh recruits they had.

During the 20s and 30s, only pilots were fully trained for their job. The other roles of an aircrew were filled by volunteers from skilled ground trades who took short-term courses in aerial gunnery and bomb aiming. Even navigation was handled by the pilots, when a dedicated navigator was deemed suitable, a second pilot was added to relieve the workload. The Air Navigation School at RAF Manston was established in 1936, and handled the training of navigation given to pilots. Conversion training to flying boats was also handled at this installation. From the start of the war until 1941 CC had only one Operational Training Unit (OTU). Officially it had to provide training to seventeen different units, and even then it was stretched so thin that it provided little more than conversion training for pilots and crews hoping to fly land-based aircraft. Bomber Command was asked to help but in 1940 they were stretched just as thin as Coastal Command was. Repeated requests to establish additional OTUs were ignored. Thus, the only OTU Coastal Command possessed was rated to train 1.1 crews per month. This proved grossly inadequate.

GOC Bowhill would lambast this pitiful state of affairs before the outbreak of hostilities, stating that any OTU should be able to produce 2-3 crews for torpedo bombers and fighters, and 2 crews for reconnaissance aircraft every month. The Air Ministry would revise their policy, but the benefits of their changes fell mostly on Bomber Command. Bomber Command was given the go ahead to merge several new squadrons into OTUs. They received several months worth of work-ups and training before the Germans invaded Western Europe, whilst the Coastal Command crews received nothing.

Location was also a large factor. Coastal Command lacked sufficient aerodromes to establish new training units even if they had received them. OTU fields required certain accommodations beyond that of regular airfields. They had to be far away enough from other operational units so as not to interfere with their operations, far away from enemy airspace to reduce the possibility of losses, and Britain had the unique issue of Scapa Flow, which prevented just moving all the training units north, because the northern sea lanes were considered an operational area. For torpedo squadrons it was even worse, as they required shallow water to practice in. The dummy torpedoes used for training had to be recoverable for repeated use. In the end, Turnberry in south-west Scotland was selected for torpedo bombing, the facility being handed over to Coastal Command from Fighter Command. Even then the first OTUs for torpedo bombers were not fully established until 1943.

The pre-war failings in training reaped a serious toll. By late 1940 there was a serious shortage of pilots and wireless operators/gunners. To help fix this in the short term, the training programme was shortened, which increased numbers taken in but also reduced the quality of personnel produced by the programme. Even with the cuts, the unit was only graduating 24 men a month, when the minimum deemed appropriate was 64. Gunnery and bombing training was removed and night flying and formation flying were reduced, and quality of personnel again dropped lower. Entry requirements also dropped, allowing more recruits to apply in the first place. Even with all of this, Bomber Command received most of the 36,000 new recruits received between 1940-42. Some of the shortage was supplemented by Commonwealth volunteers, with Canadians in particular flocking to Britain to sign up with the RAF. By 1941 over 6500 of the 36,000 recruits had come from Canada.

New tactics had to be adopted to get maximum use out of what was available. Two major changes took place in late 1940. First, the aforementioned patrols into the Bay of Biscay were an attempt to catch U-boats as they transited from their bases to their primary hunting grounds. From post-war information was can determine that this was more effective than Coastal Command believed, with both Italian and German submarine commanders noting their annoyance at being forced under, costing precious fuel and time needed to make successful intercepts. The second major decision was to begin patrolling the convoy routes directly, as opposed to general sweeps. Again, U-boat commanders note their annoyance at being unable to shadow convoys on the surface, sometimes losing hours of careful positioning when forced to dive and hide. While these tactics would pay off at the height of the battle in 1943, as it was in 1940, Coastal Command was credited with only five successful actions against the enemy. Two U-boats sunk in conjunction with RN warships, one sunk unaided, and two U-boats damaged. If purpose-built airborne ASW weapons were available, the two damaged might have have been two destroyed.

(Six RAF Coastal Command Blenheims in starboard echelon formation. These aircraft were part of No.2 (Coastal) Operational Training Unit.)