No matter what political reasons are given for war, the underlying reason is always economic.
Nothing is inevitable until it happens.
No war is inevitable until it breaks out.
Like most of those who study history, he (Napoleon III) learned from the mistakes of the past how to make new ones.
Lenin was the first to discover that capitalism 'inevitably' caused war; and he discovered this only when the First World War was already being fought. Of course he was right. Since every great state was capitalist in 1914.