Original sentence: The stab-in-the-back myth (, ) was the notion, widely believed and promulgated in right-wing circles in Germany after 1918, that the German Army did not lose World War I on the battlefield but was instead betrayed by the civilians on the home front, especially the republicans who overthrew the Hohenzollern monarchy in the German Revolution of 1918–19
Edited sentence: The stab-in-the-back theory (, ) was the notion, widely believed and promulgated in right-wing circles in Germany after 1918, that the German Army did not lose World War I on the battlefield but was instead betrayed by the civilians on the home front, especially the republicans who overthrew the Hohenzollern monarchy in the German Revolution of 1918–19