The new policy of unrestricted submarine warfare was initially a success, but by 1918 the Allied anti submarine measures had continued to become more effective and by mid-1918, U-boat losses had reached unacceptable levels, and the morale of their crews had drastically deteriorated, by the autumn it became clear that the Central Powers could not win the war. The Allies insisted that an essential precondition of any armistice was that Germany surrender all her submarines, and on 24 October 1918 all German U-boats were ordered to cease offensive operations and return to their home ports.