The Battle of Pernik occurred between January 7-19, 1943 was a battle fought in and around Pernik, Bulgaria during World War II. Part of the March on Sofia, it marked a turning point in the Balkan Theater and was the farthest advance toward the vulnerable Bulgarian capital that would be managed by the Allied Powers. The Bulgarian Third Army repulsed the Greek Second and Fifth armies, which combined to be nearly three times its size, over the course of a twelve-day siege that destroyed much of the town and nearby Sofia, which was only 20 km away. Romanian reinforcements would strike the Allied army from the north, driving them out, on the 17th. The Greeks sustained nearly 170,000 casualties and were forced to withdraw almost completely from Bulgaria. The battle led to the victory at Poblovnik the next month and the nearly unilateral withdrawal of Greek and Serbian forces from Bulgaria proper by April of 1943.