Australia entered World War I in August 1914, six months after the two submarines arrived in Australia. Initially, they were ordered into the Pacific to search for the German Pacific squadron under the command of Admiral Graf von Spree. At the time, Germany had a number of colonies in the Pacific, including New Guinea. On 14 September, the AE1 and its entire crew disappeared without a trace. The Australian War Memorial website suggests that the AE1 may have struck an uncharted reef and sank. The commander of the AE2, HG ‘Dacre’ Stoker believed that the loss of the AE1 was due to mechanical failure or an accident while diving. The remains of the AE1 are lost to this day.
In Melbourne in December 1914, AE2 linked up with ships carrying 15,000 men and 5,000 horses of the second contingent of the Australian Imperial Forces, which were being sent to the Middle East. The fleet arrived in the Mediterranean at the end of January 1915. From there, the British Admiralty ordered Lieutenant Commander Stoker and his submarine to join the Allied naval force off the Dardanelles and participate in the Gallipoli Campaign.
The Allied command sought to send submarines through the highly defended narrows of the Dardanelles into the Sea of Marmara to attack Ottoman supplies and reinforcements, hindering them from reaching the battlefields of Gallipoli. But minefields in the straits had already claimed three battleships of the British and French fleets and severely damaged three others. Two other Allied submarines had tried and failed at the same task, being destroyed in the attempt.
On 24 April 1915, AE2 first attempted to penetrate the Dardanelles. The AE2 reached 6 nautical miles (11 km) into the Dardanelles before being forced back with mechanical problems (Stevens, D, 2001, The Royal Australian Navy: A History).
At 2.30 am on 25 April 1915, AE2 re-entered the Dardanelles on the surface, trying not to be spotted by searchlights. Shortly before dawn, as the first boatloads of ANZAC soldiers were approaching the coast of the Gallipoli Peninsula, AE2, under fire from Ottoman shore batteries, dived into the heavily mined waters. Without sophisticated radar and sonar systems, their ability to pass through the minefields was a matter of chance.
On that first day, while again risking time on the surface, AE2 torpedoed and damaged the Ottoman gunboat Peyk-i Sevket. Following this engagement, AE2 was pursued by Ottoman surface vessels, running aground twice beneath the Ottoman forts along the shore. The Ottoman artillery in these forts could not fire on AE2 as the guns could not be lowered sufficiently.
By the morning of 26 April, after many hours submerged to avoid attack and only rising when absolutely necessary, AE2 had passed through the Dardanelles and entered the Sea of Marmara. Over four days she attacked enemy ships with torpedoes, but without success. On 29 April, she met the British submarine E14, which was the first of a number of submarines that followed AE2 into the Sea of Marmara. On 30 April, while attempting to rendezvous with the E14, AE2 was confronted with the Ottoman torpedo boat Sultanhisar. As AE2 attempted to dive out of danger’s way, it encountered mechanical problems and was forced again to the surface where it was attacked and fatally damaged. All on board were forced to abandon the submarine and were taken captive. Stoker and his crew ensured, however, that AE2 sank to the bottom of the sea so that the Ottoman forces would not be able to take possession of it.
Despite the AE2‘s sinking, the vessel’s wily commander and determined crew paved the way for a number of other Allied submarines to negotiate the difficult straits of the Dardanelles, causing great disruption to Ottoman supplies and reinforcements moving on and around the Sea of Marmara.