Battle of Määritsa (Estonian: Määritsa lahing,also known as Battle of Osula, Osula lahing) was a battle held in Osula village, at that time in Võru County, Estonian SSR, Soviet Union. It began on the night of 31 March 1946, involving members of the Forest Brothers and Soviet occupation forces. Seven Estonian fighters based at the Hindrik farmhouse were besieged by up to 300 Soviet soldiers. The battle lasted about seven hours before the farmhouse caught fire and the Soviets demanded that the rebels surrender. Only two fighters managed to escape alive from the farmhouse, but were subsequently killed in battle with the besiegers.