In 1949, Adan joined the Israeli Armoured Corps and founded the first M4 Sherman tank unit of the IDF. During the Suez Crisis of 1956, he commanded the 82nd battalion of the 7th Armoured Brigade in the Sinai Peninsula, decisively defeating Egyptian forces in the region. After the war, Adan became the operations officer of the Armoured Corps and later the commander of the 7th Armoured Brigade as well as the Armoured Corps School. During the Third Arab–Israeli War, he was the deputy commander of the Armoured Corps and of the 31st Armoured Division, where he once again engaged Egyptian forces in the Sinai. On , he became the commander of the Armoured Corps.