Over 5,000 Australians were among those engaged in the crucial tug-of-war over control of the shipping lanes to Britain during World War Two. They served in the Royal Australian Navy, especially HMA Ships Australia, Napier, Nestor, Nizam, Quickmatch, Perth and Quiberon, the Merchant Marine and in Royal Air Force and Royal Australian Air Force squadrons of Coastal Command, particularly 10, 455 and 461 Squadrons, helping to repel Germany’s attempt to strangle the British war economy.
This battle shaped the outcome of the war. As an island nation, Britain relied heavily on international trade to supply its war industries and feed its population, both military and civilian. Cutting its sea lanes would undermine the Western Allies’ attempt to liberate Europe. Instead, Allied warships and aircraft defeated the German U-boat campaign, enabling a massive influx of war supplies and American and Canadian troops, setting up the invasion of France in 1944, culminating in Germany’s defeat in May 1945.
It was the longest campaign of the war, being fought over the entire duration from September 1939 to May 1945. Naturally, over such a long period of time, there were multiple phases to the battle, as first one side then the other introduced new tactics and weapons.
War at sea and in the air
The tempestuous Atlantic Ocean was as much an enemy as the human foe. The combatant ships were typically small, and the U-boats, which mostly travelled on the surface, as well as the anti-submarine craft, were tossed ferociously by wild storms all year round, pitching and rolling to an alarming degree. Sailors endured miserable, wet conditions and sea sickness was rife.
Strike aircraft attacked German convoys along the European coast, often suffering heavy losses to intense anti-aircraft fire. Long range aircraft flew exhausting missions of ten or more hours, at low level through fog and storm, with sparse rewards in U-boat sightings. Occasionally, fierce battles broke out between German and British aircraft.
The most spectacular was on 2 June 1943, when an Australian-crewed Sunderland flying boat of 461 Squadron, captained by Flight Lieutenant Colin Walker, fought eight Ju-88 heavy fighters for 45 minutes, the huge Sunderland thrown around in wild evasive manoeuvres for virtually the whole time. The Ju-88s knocked out an engine, killed a crew member and wounded several others while riddling the Sunderland with hundreds of hits. In return the Australian gunners shot down four Ju-88s and drove off the rest. The crippled aircraft stagged through a 3-hour return flight, finally being beached in Cornwall. Walker was awarded the Distinguished Service Order, while other aircrew received lesser decorations. Sadly, most of the surviving crew disappeared on a mission two months later.
Phases of the Battle
Germany began the Battle of the Atlantic with the advantage of controlling the coasts of France and Norway, supplying a multitude of bases for U-boats and aircraft. They also had cracked the British naval code, and used radio direction finders to pinpoint the location of British ships. New magnetic mines were very effective, while ‘Wolfpack’ attacks by multiple U-boats overwhelmed British defences. Surface raiders such as the Graf Spee and Bismarck, as well as disguised merchant raiders, posed a threat, but these were more easily eliminated by Britian’s powerful surface fleet. Germany failed to invest in both the quality and quantity of its anti-maritime aircraft, which were soon reduced to attacks in the Bay of Biscay and along the British east coast.
The British countered by grouping ships into convoys, making them easier to protect, and by using Asdic, better known as sonar, to detect U-boats under water. America supplied 50 old destroyers to the Royal Navy, expanding the number of escort vessels available.
However, the first six months of 1942 was a high water mark for the U-boats, who nicknamed the period as ‘the happy time’. German Admiral Doenitz promoted new U-boat designs, with greater range and which were resupplied at sea with fuel, food and torpedoes by large ‘milch cow’ submarines. Hundreds of Allied ships were sunk, especially along the American coast where ships were silhouetted against city lights. As the Allies tightened their defences around their coastlines, the Germans moved to the Caribbean and central Atlantic, sinking large numbers of oil tankers, bauxite carriers and other merchant ships. In June, and again in November 1942, Allied shipping losses exceeded 700,00 tons which, if sustained, would cripple the Allied war effort.
Allied victory
The Allies hit back in the second half of the year with a growing fleet of long-range radar-equipped aircraft that could detect U-boats on the surface, plugging the gap in shore defences. Small escort carriers, nicknamed ‘baby flattops’, carried 20-30 aircraft which patrolled the waters around convoys, offering a high level of protection against U-boats. American shipyards developed simplified mass production techniques to build 2,700 ‘Liberty Ships’, each of which could be churned out in about 40 days, thus more than doubling the total tonnage despite losses to U-boats.
Allied shipyards produced hundreds of frigates, sloops and corvettes, small dedicated anti-submarine ships. The surplus from protecting convoys were formed into ‘hunter-killer’ groups which specialised in hunting U-boats.
In early 1943, the Germans had some spectacular successes against convoys, using wolfpacks of up to 60 U-boats to overwhelm some inexperienced Allied defences. They also shifted to the South Atlantic where at first the Allies had few escorts and aircraft. However, Allied superiority in resources, quality of equipment and experience soon turned the tables, and Doenitz was forced to evacuate the Atlantic in March 1944.
The Germans developed faster boats and ‘schnorkels’ allowing submarines to run their diesel engines and recharge their batteries while underwater. Defensive measures included sending false echoes to sonar operators and covering U-boats with anti-aircraft guns to counter the numerous Allied planes. The Allies continued to improve the quality of their submarine-detection radar, often surprising U-boats at night with powerful searchlights and sinking them with anti-submarine depth-charges and bombs. Corvettes were equipped with more accurate ‘Hedgehog’ mortar bombs firing ahead of the ship. ‘Enigma’ decoding of German signals revealed the location of U-boats which were hounded to death by expert hunter-killer groups. U-boats continued to prowl the Atlantic, but only singly and with less and less success.
By the end of the war, the Germans had sunk over 5,000 merchant ships totalling over 15,000,000 tons, along with the loss of 65,000 sailors, but in the process had lost 782 U-boats, about seventy per cent of their U-boat fleet.