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The Merchant Navy

Page 4 – The Battle of the Atlantic

Although it was waged half a world away, few military campaigns were as vital to New Zealand's interests as the Battle of the Atlantic. A German victory, which would have severed this country's links with Britain, was one of the gravest threats New Zealand has ever faced. The Awatea and some other locally owned ships spent time in the Atlantic, but almost all the New Zealand merchant seafarers who took part in this campaign served under the British flag – as did their many compatriots in the ships and squadrons of the Royal Navy, Fleet Air Arm and RAF Coastal Command.

The longest campaign

The Battle of the Atlantic lasted 2074 days: from 3 September 1939, the day war was declared, to 7 May 1945, the day Germany capitulated. Allied merchant ships were sunk with loss of life in the Atlantic on each of those days, and on virtually every day in between.

Germany's Atlantic strategy was simple: to starve Britain into submission by destroying merchant ships and their essential cargoes of food and raw materials faster than they could be replaced. Although mines, bombers and surface ships would claim many victims, the deadliest threat was the U-boat. The Allies' defence against, and eventual victory over, the U-boats in the Battle of the Atlantic was based on three main factors: the convoy system, in which merchant ships were herded across the North Atlantic and elsewhere in vast formations of up to 60 ships; the painstaking, secret work of Allied signals intelligence, especially the breaking of the U-boats' sophisticated Enigma code, which allowed the naval authorities to redirect convoys away from danger; and, from 1943, the deployment of longer-range aircraft and more powerful escort forces (often including small aircraft carriers).

The Battle of the Atlantic was one of the longest and most decisive campaigns of the Second World War. Had Germany succeeded in severing the transatlantic lifeline, Britain would soon have been faced with a choice between starvation and surrender. Without fuel, the RAF could not have withstood the Luftwaffe, nor could Britain have later become the 'unsinkable aircraft carrier' from which Allied air power could strike deep into Germany. The vast industrial resources of the United States could not have been mobilised in support of its British and Soviet allies. Without the ceaseless flow of troops, equipment and fuel across the Atlantic, the liberation of Western Europe could not have been achieved.

How to cite this page

The Battle of the Atlantic, URL:, (Manatū Taonga — Ministry for Culture and Heritage), updated