the seddülbahir castle

Long before the campaign, the fortress was equipped with old canons but in 1915 it had a total of 10 artillery pieces. The castle was heavily bombarded on November 3, 1914 by British warships and again on February 19, and February 25, 1915. Its artillery was totally silenced before the Allied Naval attack of March 18. However while the castle posed no threat to the Anglo-French fleet it was a real threat for the British soldiers landing at V beach (Ertuğrul Bay) on April 25.
Turkish soldiers hidden in the ruins inflicted severe casualties on the landing forces, preventing troops getting off the beach for some 12 hours. The attacking British forces only managed to secure the fort the next day. The French took over this region and the fort on April 27, using it as a supply depot, hospital and barracks throughout the campaign.

"Gallipoli Battlefield Guide", (Istanbul 2006), Gürsel Göncü & Şahin Aldoğan.