In the last days of January, 1945, the Russian troops cleared entirely the city of Pest from the Germans. The most bitter fighting, however, continued on the other side of the river, in Buda, until the middle of February. The surviving population of the city emerged from the cellars where they lived during the seven weeks of the most savage, 24-hours-a-day bombing and shelling, only to find their town half destroyed on the streets littered with corpses. Kodály lived through this hell in the cellar of the Opera house, after his flat has been partly destroyed by an aerial attack earlier in the war. It was against this background the Missa Brevis was completed early in 1942.