The Peshmerga and Barzani leadership crossed into Iraq in two waves, and though successful in overcoming the Iraqi police and "jash" forces, whom they met on their way to Barzan, Sheikh Ahmed Barzani was arrested by the Iraqi government and Mustafa Barzani was requested to surrender. When the Iraqis began to mobilize troops to seek Mustafa's defeat and surrender, he decided on evacuation towards the Soviet Union. The journey began on May 1947, with the forces of Barzani engaging in skirmishes with the Iranian military on their way.