The Greek Army rebelled in the 11 September 1922 Revolution (Επανάσταση της 11ης Σεπτεμβρίου 1922) so named as Greece remained on the Julian calendar at the time.
This confusing event followed in the wake of public upset at the loss of the Greek effort in Anatolia, proving if nothing else that defeated armies are dangerous to their own governments, if to nobody else.
The rebellion led to the abdication of the king, who was on his second reign, having suffered from military discontent during World War One as well. He'd opposed entering the war. The Greek monarchy would be restored a few days later and King George II would take over, who would also have two reigns, one ending in 1924, and a second running from 1935 to 1947.
Berryman cartoon for this day in 1922.
