F/L F.H.C. Reinke's Diary, October 1944
	Attack on U-672 by Sunderland "A", 423 Squadron

A Bristol Beaufighter of No 404 Squadron in June 1944, still bearing the distinctive markings of Allied planes on D-Day. National Defence Image Library, PL 41049.

In Great Britain air force units protecting merchant convoys from enemy submarines were placed under the control of the Royal Air Force (RAF) Coastal Command. Its mission was essentially a defensive one: air patrols ensuring convoy safety by preventing U-boat attacks. The actual destruction of the submarines remaining a secondary, albeit desirable, objective.

Before the war, the RAF and the Admiralty developed a command and control structure in order to integrate, as much as feasible, air force operations within the operational control framework of the Royal Navy. Air force and naval commands had combined headquarters and operation rooms, thus greatly improving information sharing by giving Coastal Command immediate access to Admiralty operational data. The Royal Navy superior officer had the authority over operations as a whole, since he was in a better position to gain a full picture of the situation at sea. The air group commander, for his part, had all the latitude to take appropriate measures, given his assessment of the situation and the resources available.

The depth charges and machine-guns used by the air patrols were formidable enough that a detected U-boat would dive, thereby giving up the chase. Planes were, therefore, a major deterrent. Unfortunately the Bristol Bleinheims, Lockheed Hudsons, and Handley Page Hampdens used by Coastal Command at the beginning of the war could not carry enough depth charges to destroy an enemy submarine. Moreover, the earlier depth charges were not powerful enough to seriously damage a submarine hull.

The Mark XIII depth charge, with its powerful Torpex charge and a Star detonator that could ignite it at a depth of only 5 metres, only came into use in July 1942. That improved depth charge, however, still needed to be within 7 metres of a U-boat to pierce its hull. Through the combined use of Mark XIII depth charges and of better airplanes, especially Consolidated Catalina flying boats and four-engine Consolidated Liberator bombers, Coastal Command had much better chances of destroying German submarines. The Catalina had a 25-hour flight autonomy and a 960-km range, while the Liberator, as modified to provide extra-long range, could escort a convoy over 1,600 km.

In addition to convoy escort duties, Coastal Command was responsible for offensive operations against German vessels. Several of those operations targeted areas close to U-boat bases, such as in the Bay of Biscay; their objective being to intercept and destroy enemy submarines as they left or returned to their bases. Finally, Coastal Command had some units engaged in actions against German shipping traffic; three Canadian squadrons took part in those operations.

The RCAF Squadrons

Canada, like Great Britain, was convinced that the development of the air force should concentrate on strategic bombing and fighter operations. For that reason, the RCAF’s overseas aeronaval involvement was limited to eight squadrons. Let us not forget that the RCAF was also responsible for protecting maritime traffic along the coasts of Canada within the framework of the Home War Establishment mandate.

A Beaufighter, flown by Lt L.C. Boileau, 404 Squadron, firing rockets at German merchantmen Aquila and Helga Ferdinand near Fjord Migdulen, November 8th, 1944. Both ships were sunk. National Defence Image Library, PMR 93-073.

The first RCAF squadrons to serve under the British Coastal Command were formed in Great Britain in 1941. Three squadrons, No 404, No 407, and No 415 took part in attacks against German ships along the coasts of north-western Europe. Equipped with Bristol Beaufighters in the spring of 1943, No 404 played a role in the development of a new weapon, the three-inch (7,6 cm) rocket with a 25-pound (11.3 kg) armour-piercing charge, as it hunted down Axis ships off the coasts of Norway. After an initial period where it flew Blenheim and Hudson light bombers, No 407 Squadron received twin-engine Vickers Wellingtons. Those were improved aircraft that allowed No 407 to attack and sink more ships than any other squadron of its group. No 415 Squadron, for its part, experienced many frustrations as its planes were poorly suited for their missions, and as it was frequently forced to relocate. Those problems were solved in 1944 when the squadron was assigned to Bomber Command.

No 413 Squadron was created in the summer of 1941 and equipped with Consolidated Catalina flying boats, then one of the best aircraft for anti-submarine warfare. Less than a year later, the squadron was transferred to Southeast Asia where the Japanese fleet threatened to annihilate the Royal Navy and invade Bengal. No 413 Squadron’s first Catalina reached Koggala in Ceylon (today Sri Lanka) on March 28th, 1942. Patrols started a few days later on the morning of April 4th.

In Koggala, an airstrip is being built for No 413 Squadron’s Catalinas, February 10th, 1943. Coolies quarried, crushed and carried all the stone required without any mechanical help. National Defence Image Library, PL 18412.

On his first patrol, after twelve hours of unsuccessful search, Squadron Leader L.J. Birchall and his crew of eight located the Japanese fleet. They closed in to assess the number of warships but were rapidly spotted by Japanese Zero fighters that were covering the ships. The Zeros attacked the Catalina that Birchall tried desperately to keep in flight while the wireless operator sent in coordinates of the fleet. The badly damaged plane dived and Birchall, together with six of his crewmates, managed to get away from the wreck, only to be rescued by a Japanese destroyer and made prisoners of war. Birchall’s call, however, had warned the Allies that a Japanese attack against the island was imminent and earned him to be known as “the Saviour of Ceylon”,

After the April and May 1942 Japanese attacks, the Southeast Asia theatre grew much quieter and months after months of monotonous patrolling were to be the lot of No 413 Squadron.

See Squadron Leader Len Birchall’s story in "Ceylon’s Saviour ", The Sunday Times, April 7th, 2002

Created in 1942, No 422 and No 423 Squadrons flew aboard Short Sunderland flying boats. Those were heavy, four-engine aircraft with less autonomy and range than Catalinas; they had been originally designed for passenger service. The hull was actually so huge that it could be fitted with two decks. On the lower deck a small kitchen equipped with an oven provided the crew with a wartime luxury: coffee and hot meals.

A Short Sunderland of No 422 Squadron landing at Castle Archdale. National Defence Image Library, PL 40996.

9 Oct /44, Monday, Castle Archdale. Just for a change, here we are over in north-west Ireland, on Lough Ewe, about 20 miles from the west coast. Sunderlands and Catalinas are the vehicles here.
F/L F.H.C. Reinke’s Diary, October 1944

Given the defensive nature of their missions, most Coastal Command squadrons had to fly lengthy patrols without even a glimpse of the enemy. Bad weather was actually a worse threat. Patrols followed one another and men had to fight boredom that would make them less vigilant. Encounters with the enemy may have been rare but they certainly were not without danger. U-boats were tough targets for planes to fire at, and one had to get really close to get a hit. With its machine-guns and anti-aircraft 20-mm guns, a U-boat could certainly fire back in a sustained manner (Type IX U-boats even had an additional 37-mm gun). Risks were high and so were losses in lives and material.

At 1339 hours on 24th April, 1944, Sunderland A/423 was flying at 2100 feet when the captain saw visually a wake bearing 175°T distant 16 miles. Speed was increased to 140 knots while the second pilot confirmed with the binoculars that the wake was that of a U-Boat…
Attack on U-672 by Sunderland "A", 423 Squadron

An average of 2,000 to 3,000 Canadians served with the Coastal Command during the war’s last two years. In April 1944 the aircrews, ground personnel and administrative support personnel of all RCAF squadrons amounted to 2,065 men; 919 more Canadians were with various RAF units.