The Attack on Hrubieszów was a joint action of the Polish post-Home Army (AK) organization Freedom and Independence (WiN) and the Ukrainian partisans of the Ukrainian Insurgent Army (UPA), which took place on the night of 27 May 1946. It was the most significant joint action carried out by these two organizations, which had previously often fought one another, but which decided to cooperate in the face of the common threat from the Polish communists and the Soviet NKVD.