Early in 1942, the Japanese seized the natural port of Rabaul on New Britain Island. This was to protect its existing base at Truk, in the Carolines, and also to provide a forward base for operations in New Guinea, the Solomon islands, and points further south.
Over time, the garrison at Rabaul rose to over 100,000 men. (It was isolated and bypassed by the Allies, and the forces were eventually left to "wither on the vine.") If there were actually 100,000 men on Rabaul at the appropriate time, some 50,000-75,000 of them could have been used to help the Japanese win key battles in New Guinea or Guadalcanal in the fall of 1942.
This did not happen of course, and I wonder why. The most obvious explanation is that most of the "100,000" men arrived on Rabaul after the key battles had been decided in the Allies' favor. A second, and related explanation is that Japanese soldiers sent to the South Pacific were sent first to Rabaul, for distribution to the other areas as needed. Then Allied naval and air activity hindered this "distribution" process, leaving an inordinate number of Japanese troops backed up on Rabaul. This "hindering" process, of course, increased as time went on.
So when did Japanese reinforcements actually arrive on Rabaul, and what did this mean for Japanese activities in the region?