 They spent much of the war rotating between the bases at Taranto, Brindisi, and Valona, but did not see combat.On 14–15 May 1917, three light cruisers of the Austro-Hungarian Navy raided the Otranto Barrage; in the ensuring Battle of the Strait of Otranto, "Regina Elena" and her sisters raised steam to assist the Allied warships, but the Italian commander refused to permit them to join the battle for fear of risking their loss in the submarine-infested Adriatic.Under the terms of the Washington Naval Treaty, Italy was permitted to retain "Regina Elena" and her three sisters.