Nevertheless, by spring 1917 the National Defence had brought her three divisions to the Macedonian front, and formed the National Defence Army Corps under Zymvrakakis. The victorious Battle of Skra-di-Legen in May 1917 served as the baptism of fire for the Army of National Defence. A month later, King Constantine I was forced to abdicate by the Allies, and was succeeded by his second son, Alexander. Venizelos returned to Athens as Prime Minister and virtual dictator.