http://www.onwar.com/chrono/1943/apr1943/f12apr43.htm
Mass graves uncovered in Katyn Forest
Monday, April 12, 1943 www.onwar.com
Germans show local Poles evidence from Katyn massacre [photo at link].
In Occupied Poland... The Germans announce the discovery of a group of mass graves in the Katyn Forest. The bodies of 4100 Polish officers killed by the Soviets during their occupation of the region, are found.
In Tunisia... The retreating Axis forces reach Enfidaville.
In New Guinea... Port Moresby is attacked by 174 Japanese aircraft in their ongoing offensive. Little significant damage is done.