The one of the reason's why the Allies allied themselves with the soviets was because they wanted to open a new front. The Soviet Front would be so massive and would force Axis's units to spread even more, and to spread resources more. Though they were already spread out.
The major cause of shifts in political allegiance during this time came from the Great Depression, which required strong government intervention to correct the issue. These interventions became commonly ascociated with the Democratic Party, thanks to FDR.
The widespread sentiment that influenced the rise of totalitarianism was a fear of instability and the rise of nationalism in countries like Germany and Italy. Authoritarian leaders crystallized the notion that a singular leader, a strong military, limited dissent and nationalism were the ingredients necessary for a strong state. This became a normative framework in Germany and Italy.
