The Trans-Siberian Railway was built between 1896 and 1902. Construction of the scenic railway around the southwestern end of Lake Baikal required 200 bridges and 33 tunnels. Until its completion, a train ferry transported railcars across the lake from Port Baikal to Mysovaya for a number of years. The lake became the site of the minor engagement between the Czechoslovak legion and the Red Army in 1918. At times during winter freezes, the lake could be crossed on foot—though at risk of frostbite and deadly hypothermia from the cold wind moving unobstructed across flat expanses of ice. In the winter of 1920, the Great Siberian Ice March occurred, when the retreating White Russian Army crossed frozen Lake Baikal. The wind on the exposed lake was so cold, many people died, freezing in place until spring thaw. Beginning in 1956, the impounding of the Irkutsk Dam on the Angara River raised the level of the lake by .