Japan used this designation for the main portion of the battle. The overall plan for MO was first to seize Tulagi on May 3rd and secure Port Moresby by May 10th. Sounds simple and straight forward, but it really is not. Major actions like this were actually complex movements. Japan was known for its planning execution of complex, yet effective, military operations.

Japan’s military operations of the time were much like playing chess. When you make a move you are looking ahead to your next move. You set your pieces up to provide defense, but also keep and eye on the end prize, the king. In the case of Operation MO the prize was cutting of Australia.

The goal of taking Port Moresby would help to secure the island of New Guinea and open the way to expanding south to New Caledonia and east to Fuji. Furthermore direct attacks on Coen, Cooktown and Townsville in Queensland were planned as these were ports receiving supplies from the US. One final step would be the capture of Thursday Island to the north of Cape York.

The control of these islands would provide the Japanese Navy with plenty of bases to launch air patrols and strikes against shipping in the area. It would also force the US and Australia to withdraw its Naval forces from the immediate area. Japanese submarines would also have forward bases from which to harass allied shipping. Not only this but rich phosphate mines were located on Nauru and Banaba Island.

The plan was complex, but it was well thought out. To counter the move the US and Australia sent in the forces they could spare and just hoped to get in a couple lucky hits. Prior to this operation aircraft were not the main focus of the operation, that was to change quickly.


NOTE:
Map is from Wikipedia