Birger Wasenius was the next great Finnish speed skater after Clas Thunberg. Wasenius made his international début at the 1933 European All-around Championships, where he medaled in all distances (silvers at 5 and 10K, and bronzes at 500 and 1,500), but still had to settle for a silver medal in the all-around behind Norwegian Ivar Ballangrud. Wasenius competed at the 1934 World All-around Championships where he won the 5,000, but again had to settle for a silver in the all-around, this time behind another Norwegian, Bernt Evensen. The two Norwegians would be his closest competitors throughout his career. In 1935 Wasenius was third at the European All-around Championships and a disappointing sixth at the World All-around Championships. Before the 1936 Winter Olympic Games, Wasenius won the 10K at the World All-around Championships, but had to settle again for a silver medal in all-around behind Ballangrud. In Garmisch-Partenkirchen Wasenius won three medals (silvers at 5 and 10K and bronze in the 1,500) and was eighth in the 500. The 10,000, in which Wasenius was paired with Ballangrud, is considered one of the greatest and most exciting races in speed skating history. Ballangrud started at a faster pace than Wasenius, and Wasenius tried to adjust his pace to catch him, without succeeding. After 4,400 m he was too far behind Ballangrud and backed off, concentrating instead on beating Austrian Max Stiepl, whose half-way time Wasenius had equaled, and he managed to beat Stiepl by 1.8 seconds. In 1937 Wasenius again won bronze at the European All-around Championships and silver at the World All-around Championships, but his 1938 season was a disappointment, placing only ninth at the European and sixth at the World All-around Championships. At the 1939 European All-around Championships Wasenius was fourth, while winning his only European distance title in the 500. But at the 1939 World All-around Championships Wasenius finally managed to beat the Norwegians to win the title, while winning his third World distance title, in the 1,500, and placing second in the other three distances. Domestically Wasenius was Finnish all-around champion six times (1933-1935, 1937-1939). Less than a year after his World Championships victory, Sergeant-Major Wasenius was killed in action in the Winter War between Finland and the Soviet Union.
Personal Bests: 500 – 43.4 (1938); 1500 – 2:18.2 (1937); 5000 – 8:21.3 (1937); 10000 – 17:28.2 (1936).