The "River Clyde" beached at 06:22 on 25 April 1915, and the plan called for a steam hopper to form a bridge from the ship to the shore. However, the Dardanelles current swept the hopper away so Unwin, accompanied by Able Seaman William Charles Williams, who had served under him on the "Hussar" and had been ordered to stay by his side, dove overboard and manhandled two lighters into position, lashing them together to form the bridge. All the while Unwin was under fire from the Turkish defenders. When Williams was mortally wounded, Unwin went to his aid and the lighter he was holding was swept away.