If you're interested in this sort of thing, definitely look up "Perpetual War for Perpetual Peace," or at the very least go read a summary. Also fascinating stuff.
Basically, PWFPP's argument is that Nazi Germany would've been very weak and able to overthrow easily by resisting the Nazi conquest of Czechoslovakia - the Czech army was a decent fighting force, and with allied support could've dismantled Nazi Germany right there.
France and England do nothing there, but then declare war on Germany after Germany and the Soviet Union sign a peace treaty and jointly invade and divide Poland, and then inexplicably France and England don't attack. That was the stupidest possible way to declare war. You could've backed the Czechs, but declaring war without an invasion while giving Hitler nine months to plan and let him have first strike/blitzkrieg against France? Totally stupid.
The Western front of WWII was gravely mismanaged until Winston Churchill took over in England. Like, ridiculously so. They had quite a few opportunities to smash Hitler before he became a problem. When they finally did declare war, they just kind of skirmished a little while letting him build and prepare more, and letting him determine the time and place of battle (they overran the totally ineffective Maginot Line in one spot, spread quickly, and conquered France in three days).
Anyway, I do buy that theory. Germany wasn't so strong when they invaded Czech, and the Czechs are strong, tough, proud people. Declare war there and WWII basically doesn't happen. As an added bonus, the Soviet Union couldn't have absorbed Poland, East Germany, and the Baltics as a result. Man oh man WWII was grossly mismanaged in the start of it...