During the Fall of 1918, first Austria-Hungary, then Germany suffered significant defeats, which served as a catalyst for the accedancy of various anti-war factions. In Austria-Hungary that meant mutiny, desertion, and mass surrender in the army and nationalist revolutions at home. Germany, fearing a similar crisis rushed to sign an Armistice with the Entente at any cost.
Yet, just a generation later, the belligerents of WW2 faced (at least in appearance) far worse military crises and defeats, but maintained their political solidarity. For example, Britain after the Fall of France, the Soviet Union during Barbarossa, and Germany after Bagration and Overlord.
Why was this the case? How was political solidarity maintained through WW2, and how did it differ from WW1 a generation earlier?
Edit: I should say that the premise of my question reflects only a layman's understanding of events, so please feel free to correct or complicate anything you feel is incorrect, or overly simplistic.
The big difference after WW2 at least with regards to Germany and Japan was that the US needed them as a bulwarl against the Soviets. France and England wanted something between them and the USSR and a weak Germany wasn't enough. After WW1, what France and England wanted was weak Germany and that's what they got, they also didn't have much interest in propping up Austro-Hungary either and Russia wasn't much of a threat at the time.