After his defeat at Sarıkamısh, Enver returned to Istanbul (Constantinople) and took command of the Turkish forces around the capital. He was confident that the capital was safe from any Allied attacks. The British and French were planning on forcing the approaches to Constantinople in the hope of knocking the Ottomans out of the war. A large Allied fleet assembled and staged an attack on the Dardanelles on 18 March 1915. The attack (the forerunner to the failed Gallipoli campaign) was a disaster, resulting in the loss of several ships. As a result, Enver turned over command to Liman von Sanders, who led the successful defence of Gallipoli. Enver then left to attend to pressing concerns on the Caucasus Front. Later, after many towns on the peninsula had been destroyed and women and children killed by the Allied bombardment, Enver proposed setting up a concentration camp for the remaining French and British citizens in the empire. Henry Morgenthau, the American ambassador to the Ottoman Empire, convinced Enver not to go through with this plan.