In January 1941, Student was named commanding general of the "XI. Fliegerkorps", the newly formed command for the expanding German airborne forces. In May 1941, Student directed Operation Mercury ("Unternehmen Merkur"), the airborne invasion of Crete, defended by British, Greek and Commonwealth forces. Crete was taken, in what became the "Fallschirmjäger"'s greatest victory, but the high casualties caused Hitler to forbid future major airborne operations.