How do you think the depression in Europe could be a catalyst for war?

Answer 1

Traditionally, countries experiencing a depression become more and more desperate for a solution - any solution. A politician that can promise and deliver economic relief can generally ride that popularity to cover for less agreeable programs. When mainstream politicians fail, extremist politicians gain prominence and a certain level of appeal that they otherwise wouldn't have. Mussolini and Hitler rose to power in Italy and Germany because the preceeding governments utterly failed to deal with the Great Depression. They then turned around and appealed to nationalistic pride to bully their neighbors.

The alternative isn't complex - mainstream politicians have to step up to the plate and be effective. Many historians have noted that FDR's ability to deliver on his economic promises (or at least appear to have delivered) helped marginalize socialist, communist, and fascist parties in the US.