The 1st Polish Army was a Polish Army unit formed in Sielce, near the Oka river in 1943. It operated under the auspices of the Red Army. Main battles included Battle of Lenino also known as Battle of Miereja River and Battle of Berlin.

In the latter the 1st Polish Army (78,556 soldiers) took part in the battle when on April 16 it crossed the river Oder. Among other actions, the Polish units crossed the Hohenzollern Canal and continued their advance on Kremmen, Flatow, Paaren and Nauen. They ended their campaign by participating in the capture of the Brandenburg Gate.