[Jimbuna]

I'm certainly no expert on Japanese military doctrine but what has always amazed me is the fact that a country who had as much time as they required to work out their plan/strategy for the conquer and domination of south east asia they failed in two vitally important areas in terms of the means they would carry out their plans.

1. The IJN was designed to wage a surface war backed up by a proficient air assault component yet lacked a sufficiently potent ASW capability to protect the transportation of its army to the lands it conquered.

2. (As already pointed out) A lack lustre armour and artillery element to support the army in holding the conquered territory.