An outnumbered, outgunned, lower morale force with fewer leaders must come into close contact (night) with expert night assault combat forces with high morale. With three column shifts for assault combat (leader, morale, Japanese) for Japanese units, that is exactly what the Japanese player wants to see. With equal rolls the Aussies are most likely doomed.

In my case the rolls were slanted towards the Aussies. They started out holding their own, and in fact inflicted the first step loss. Overall they performed well in combat, inflicting two steps to three received (plus a leader on either side). But the Japanese break through and scarf enough hexes to win while the remaining Aussies are locked in assault combat with no leader (demoralized hiding in the village).

Just too much advantage for the Japanese.