Denmark-Norway (though only Norwegian) ski troops were used against Sweden during the 1807–1814 Napoleonic Wars.
World War I
During WWI the Italian Army raised 88 Alpini Battalions. Their purpose was to fight summer and winter in the highest regions of the Alpine Arch. Most of the battalions were dissolved after WWI. Only nine Alpini regiments remain in service today, and only four still train every soldier in ski warfare: the 4th Alpini Parachutist Regiment, 5th Alpini Regiment, 6th Alpini Regiment and 7th Alpini Regiment.
World War II
Ski troops played a key role in the successes of the Finnish war effort against the Soviet Union during the Winter War in 1939. Forested, rural terrain with no roads was used by Finnish ski troops with great success against the advancing mechanized Soviet troops. In the Battle of Suomussalmi, two Soviet mechanized divisions (45,000 men) were annihilated by three Finnish regiments (11,000 men).
The Soviet Union deployed 11 ski battalions, among other troops, in November 1941 to reinforce their defenses in the Battle of Moscow.
The most common transportation for Norwegian soldiers during the Norwegian Campaign in 1940 was skis and sleds, and in Operation Gunnerside, paradropped Norwegian commandos covered a large distance using skis in order to reach and sabotage the heavy water plant Vemork at Rjukan in Telemark, Norway, which was being used by the Germans as part of their nuclear research programme.
Ski warfare even extended to the Middle East where the Australian Ski Corps were deployed against Vichy French forces in the mountains of Lebanon.
Also during WWII, the United States Army 10th Mountain Division was established and trained for ski combat. They were deployed in Italy.