The God of Battles will throw the dice that decide...
No war is inevitable until it breaks out.
Bismarck fought 'necessary' wars and killed thousands, the idealists of the twentieth century fight 'just' wars and kill millions.
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.
Though the object of being a Great Power is to be able to fight a Great War, the only way of remaining a Great Power is not to fight one.
No matter what political reasons are given for war, the underlying reason is always economic.
The great armies, accumulated to provide security and preserve the peace, carried the nations to war by their own weight.