Exercise DATELINE PARTNERS began at the scheduled time. Like most such war games, it was a combination of free play and strict rules. The size of the Pacific Ocean made for ample room, and the game would be played between Marcus Island, a Japanese possession, and Midway. The idea was to simulate a conflict between the U.S. Navy and a smaller but modern frigate force, played by the Japanese Navy. The odds were heavily loaded against the latter, but not completely so. Marcus Island—called Minami Torishima on their charts—was, for the purposes of the exercise, deemed to be a continental land mass. In fact the atoll consisted of a mere 740 acres, scarcely large enough for a meteorological station, a small fishing colony, and a single runway, from which would fly a trio of P-3C patrol aircraft. These could be administratively "shot down" by American fighters, but would return to life the next day. The commercial fishermen who also maintained a station on the island to harvest squid, kelp, and the occasional swordfish for their home markets welcomed the increased activity. The airmen had brought a cargo of beer which they would exchange for the fresh catch in what had become a friendly tradition.

Two of the three Orions lifted off before dawn, angling north and south, to search for the American carrier fleet. Their crewmen, aware of the trade problems between the two countries, concentrated on their mission. It was not an unknown mission to the Japanese Navy, after all. Their forefathers had done the same thing two generations before, in Kawasaki H8K2 flying boats—the same contractor that had built these Orions—to search for the marauding carriers commanded in turns by Halsey and Spruance. Many of the tactics they would employ today were based on lessons learned from that earlier conflict. The P-3Cs themselves were Japanese models of an American design that had begun life as turboprop airliners, then matured into rugged, powerful, if somewhat slow maritime patrol aircraft. As with most Japanese military aircraft, the American products had stopped at the basic profile. The power plants had since been developed and improved, giving the Orions a cruising speed boosted to 350 knots. The internal electronics were particularly good, especially the sensors designed to detect emissions from ships and aircraft. That was their mission for the moment, to fly out in large pie-shaped segments, listening for radar and radio signals that would announce the presence of American ships and aircraft. Reconnaissance: Find the enemy. That was the mission, and from press accounts and conversations with family members who worked in their country's economy, thinking of Americans as the enemy didn't even come all that hard.