That was the first major war to use heavy machinery such as tanks, planes, shotguns, etc. and nations did not know how to counter these things. They were all still in old war mindsets where you March in lines for example, and by the time they figured out that they needed to change, many lives had already been lost. Not to mention trench warfare, where thousands of men threw themselves at the enemy just to gain a little bit of ground on them.
The policy of appeasement was a bid to reach a peaceful understanding with Germany. The Germans invaded Poland on September 1st 1939 and on the 3rd Britain declared war
It was "the New Jersey Plan" that was designed to favor small states, since New Jersey wanted representation in Congress to be set a certain number, instead of being relative to population size.
