Ten percent of the deaths at Flossenbürg occurred before 1943. The quarries caused the death rate to be higher at Flossenbürg than at camps with less physically demanding industries, such as brickworks; the switch to armaments production in 1943 led to a decrease in the death rate. Prisoners also suffered from a shortage of fresh water, due to the elevation, and unusually cold and wet weather; their clothing was not adequate for these conditions. The main camp, situated in a narrow valley, had little room for expansion. Originally constructed for only 1,500 prisoners, the population of the main camp increased to between 10,000 and 11,000 before it was evacuated in April 1945. In order to increase productivity, the prisoners were forced to sleep and work in shifts. This also helped alleviate the chronic overcrowding in the barracks.