One year prior to his graduation, Sukarno and Hatta proclaimed the independence of Indonesia on 17 August 1945. The warlords and rulers in Aceh urged their people to fight for independence. After his graduation, Ismail went to the Islamic Junior High School of Banda Aceh. Alongside his studies, Ismail joined the struggle for the independence, and he was appointed as the Head of the Staff Commando III of the Islamic Student Army (TPI) until 1950. He also joined the Mujahiddin Warriors from 1945 until 1947, a similar organization to TPI. He graduated the school in 1949, on which the Indonesian sovereignty was recognized by the international community.