How long was world war two suppose to last?

Answer 1

I assume this question refers to the Second World War. Well, of course, when the war started I don't think it was necessarily expected to become a world war. Certainly, Nazi Germany aimed to be in control of events and expected the invasion of Poland to be just one of a series of small wars against its immediate neighbours. However, Britain and France declared war on Germany which ensured the war would not be short or as local as Hitler had planned or hoped for. All wars are intended to be as short as possible while still achieving the war aims of the combatants.

Answer 2

Once the Nazis were defeated in Europe, the Allies considered several options for defeating Japan. Most involved some form of ground invasion similar to that used in Europe (Normandy, 1944) but with air attacks provided by B-29 bombers that were larger and more powerful than the B-17s and Lancasters that were the mainstays in Europe.

Regardless, it was expected that the Army of Japan would resist even more fiercely than the Nazis. The estimates of the Allied general command were that a ground invasion using conventional means would last until 1948 at best and at worst until 1950 or later, with a loss of as many as a million Allied personnel. Those numbers tilted the balance in favor of using the newly-developed atomic bomb to end the war more quickly.