White Friday occurred during the Italian Front of World War I, when an avalanche struck an Austrian barracks on Mount Marmolada, killing 270 soldiers. Other avalanches the same day struck Italian and other Austrian positions, killing hundreds. According to some reports both sides deliberately fired shells into the weakened snowpacks in an attempt to bury the other side. Historical documents suggest at least 2,000 victims among the soldiers and a few dozens among civilians.
https://en.m.wikipedia.org/wiki/White_Friday_(1916)