The US Army 10th Division aka the 10th Army Mountain Division factors huge when considering the history of Alpine skiing in the United States. Many soldiers from this division are responsible for opening up many ski resorts in the US and for promoting the sport of Alpine Skiing. However, the division is typically going uphill instead of downhill, after all, in war the side with the high ground has the advantage and rarely opts to move downhill.
The Wikipedia has a substantial entry on the US 10th Army Mountain Division. However, the division itself documents its history. Essentially, the Finish resistance against the Soviet invasion of 1939 motivated the formation of the division. The Fins while not repelling the Soviet Invaders made the Soviet invaders pay dearly for the invasion, and the Finnish soldiers maneuvered on cross-country skis and whacked two Russian tank divisions. That inspired Charles Minot Dole to lobby the War Department to train mountain troops.
That training included many mountain skills including downhill skiing.
However, history shows the division spent more time going uphill than downhill (expect that in battle) and in general most of the references to skiing in war involve the use of cross-country skis and not alpine skis. I can find only fleeting reference to fighting in WWI in the Vosges where French soldiers skied in attack mode, they were attacking well established German positions with the expected results, the Germans held killing the French attackers.
The US 10th Army Mountain Division is an active unit with lots of time spent in Afghanistan. It has a well established and proud history going uphill to dislodge the enemy in high mountain positions. When the soldiers who fought in the US 10th Army Mountain Division in WWII returned home, many of them founded today’s ski resorts or in other way greatly steer the direction of skiing in the USA.
Many believe fire plays an important role in the ecology of the Western plain states.