The Australian submarine (Lieutenant Commander Henry Stoker) penetrated the Straits on the night of 24/25 April. As landings began at Cape Helles and ANZAC Cove at dawn on 25 April, "AE2" reached Chanak by 06:00 and torpedoed a Turkish gunboat believed to be a Peyk-i Şevket-class cruiser and evaded a destroyer. The submarine ran aground beneath a Turkish fort but the Ottoman gunners could not bring their guns to bear and "AE2" was manoeuvred free. Shortly after refloating, the periscope was sighted by a Turkish battleship firing over the peninsula at Allied landing sites and the ship ceased fire and withdrew. "AE2" advanced toward the Sea of Marmara and at Stoker decided to rest the boat on the seabed until nightfall. At around , "AE2" surfaced to recharge batteries and sent a wireless report to the fleet. The landing at Cape Helles was going well but the landing at Anzac Cove was not as successful and the Anzac commander, Lieutenant General Sir William Birdwood, contemplated the re-embarkation of his troops. The success of "AE2" was a consideration in Birdwood deciding to persist and reports about "AE2" were relayed to the soldiers ashore to improve morale. Stoker was ordered to "generally run amok" and with no enemies in sight, he sailed into the Sea of Marmara, where "AE2" cruised for five days to give the impression of greater numbers and made several attacks against Ottoman ships, which failed because of mechanical problems with the torpedoes.