The interwar period is generally underrated in accounts of military history. The focus, in so far as there is one, is on the two world wars, with the interwar period seen as the sequence to World War One and the preparation for World War Two. The widest-ranging post-war struggle, the Russian Civil War, stemmed from World War One, the pressures of which had led to the revolutionary overthrow of the ruling Romanov dynasty in 1917. The subsequent civil war, between the Bolsheviks and their opponents, was complicated by international intervention against the former, particularly by Britain, France, Japan, Poland and the USA. In the interwar period, the USA, Japan and Britain made the greatest advances with naval aviation and aircraft carriers; more so than France and, in particular, Italy and Germany, in all of which the stress remained on battleships and battle-cruisers.