On 30 April, the submarine "AE2" began to rise uncontrollably and surfaced near the , then dropped precipitously below the safe diving depth, then broke the surface again at the stern. "Sultanhisar" immediately fired on the submarine, puncturing the pressure hull. Stoker ordered the company to abandon ship, scuttled the submarine and the crew was taken prisoner. "AE2"s achievements showed that it was possible to force the Straits and soon Ottoman communications were badly disrupted by British and French submarine operations. On 27 April, (Lieutenant Commander Edward Boyle), entered the Sea of Marmara on a three-week patrol, which became one of the most successful Allied naval actions of the campaign, in which four ships were sunk, including the transport "Gul Djemal" which was carrying and a field battery to Gallipoli. While the quantity and value of the shipping sunk was minor, the effect on Ottoman communications and morale was significant; Boyle was awarded the Victoria Cross. Following the success of "AE2" and "E14", the French submarine attempted the passage on 1 May but struck a mine and was lost with all hands. (Several weeks earlier another French boat, , had been lost after running aground near Nagara Point.)