It was not the only Polish formation that fought along the Allied side, nor the first one in the East - although the first Polish force formed in the USSR, the Anders Army, had by that time moved to Iran. The Polish forces soon grew beyond the 1st Division into two major commands - the Polish First Army commanded by Zygmunt Berling, and the Polish Second Army headed by Karol Świerczewski. The Polish First Army participated in the Vistula–Oder Offensive and the Battle of Kolberg (1945) before taking part in its final offensive with the Battle of Berlin.