it depends what war we are talking about here. if it was the second world war then no it wasn't inevitable due to Hitler breaking the terms of the Treaty of Versailles such as remilitarising the Rhineland, annexing Austria, invading Czechoslovakia and then finally Poland, had the allies from WWI stopped Hitler at the Rhineland stage we may not have had a second world war. the first world war that was a chain of events that had they been sorted out at the beginning there may not have been a war at all and so never a second world war