'Crossword' was the Allied designation of the secret negotiations between the Germans and the Americans and British, conducted in Switzerland through Italian intermediaries, to arrange a local surrender of the German forces in northern Italy, and otherwise known as 'Sunrise' (ii) (spring 1945).
These negotiations greatly disturbed the Soviets, who accused the western powers of trying to reach a separate peace, but the surrender in Italy was nonetheless signed on 29 April 1945 and became effective on 2 May.