Today marks the 75th anniversary of the bombing of Kassa (Košice), then part of Hungary and now part of Slovakia.
On the night of June 26, 1941, unidentified aircraft struck Kassa. The attack became the pretext for Hungary to declare war on the Soviet Union the following day, but it is unknown whether the Soviets were responsible for the bombing.
One possibility is that Soviet bombers mistook the city for city of Prešov (Eperjes), in Slovakia, which was already at war. Another theory was that it was a false flag attack by the Germans to provoke Hungary into the war.