[dicemoose]

One underlying reason for the split between the Imperial Japanese Army, and Navy was that the Army was generally made up of members of the Choshu clan who were rivals of the Satsuma clan that was mostly responsible for the Navy.

The two clans put their rivalries aside temporarily to overthrow the Tokugawa Shogunate, but from the Meiji Era the rivalry was responsible for the lack of coordination between the Army, and Navy through the Second World War. [1]

[1] http://en.wikipedia.org/wiki/Gunbatsu#Hambatsu