Rapid became a dominant force during the years between the world wars, an era in which Austria was one of the leading football nations on the continent. It won its first hat-trick of titles from 1919 to 1921. After the annexation of Austria to Germany in 1938, Rapid joined the German football system, playing in the regional first division Gauliga Ostmark along with clubs such as Wacker Wien and Admira Vienna. Rapid would be the most successful of these clubs. They won the Tschammerpokal, predecessor of today's DFB-Pokal, in 1938 with a 3–1 victory over FSV Frankfurt, and followed that with a German Championship in 1941 by defeating Schalke 04, the most dominant German club of the era. The team was able to overcome a 3–0 Schalke lead to win the match 4–3.