Breaching the Marianas: The Battle for Saipan

Northern Marianas American Memorial

American Memorial Park honors the American and Marianas people who gave their lives during the Marianas Campaign of World War II. 5,204 names are inscribed on a memorial which was dedicated during the 50th Anniversary of the Invasion of Saipan. Within the 133-acre boundary are white beaches, sporting areas, picnic sites, playgrounds, walkways, and a 30-acre protected wetland and mangrove forest.

Saipan's Legacy

US troops on beach at Saipan
US troops on beach at Saipan

NPS

The campaign on Saipan had brought many American casualties, and it also heralded the kind of fighting which would be experienced in subsequent operations in the Central and Western Pacific in the days that lay ahead in the Pacific War. Holland Smith declared it "the decisive battle of the Pacific offensive" for it "opened the way to the home islands." Japanese General Saito had written that "the fate of the Empire will be decided in this one action." A Japanese admiral agreed, "Our war was lost with the loss of Saipan" It had truly been a "strategic strike" for the United States.

The proof of these fundamental judgements was dramatized four months later, when 100 B-29 bombers took off from Saipan bound for Tokyo.

There were other fateful results. The United States now had a secure advanced naval base for further punishing strikes close to enemy shores. Emperor Hirohito was now forced to consider a diplomatic settlement of the war. The militaristic General Tojo, the Premier, and his entire cabinet fell from power on 18 July, nine days after Saipan's loss.

The lessons learned in this campaign would be observed in future American operations, as flaws were analyzed and corrected. The clear need to improve aviation support for the ground troops led directly to the better results in the Philippine Islands and on Iwo Jima and Okinawa. The artillery-spotting missions flown by VMO-2 and -4, set a pattern for the use of the light planes in the future.

Naval gunfire support was also closely reviewed. General Saito had written, "If there just were no naval gunfire, we feel we could fight it out with the enemy in a decisive battle." While more than 8,500 tons of ammunition were fired by U.S. Navy ships, the flat trajectory of the naval guns "proved somewhat limiting," as the shells didn't have the plunging and penetrating effect which was needed against Japanese strongholds.

Finally, there were lessons learned from the supply confusion that had marred the early days on the beaches and hadn't improved much since the days of the Guadalcanal landing. Logistic problems had arisen because, once a beach was in friendly hands, the ships were unloaded as rapidly as possible and the sailors in the landing craft were in a hurry to get into the beaches and back out again. Supplies were spread all over the beach, partly because of the enemy's artillery and mortar harassing fire on the beaches, but also because of the corps' hard-driving, rapid attack, the estimate of resupply requirements was far too small. For example, a shortage of radio batteries was never corrected. There was insufficient time to sort and separate equipment and supplies adequately. Consequently, there were mix-ups, with Marine uniforms getting into Army dumps and Army supplies showing up in Marine dumps.

It was after the beach confusion at Saipan that the Navy decided a permanent corps shore party should be organized. It would be solely responsible for the movement of all supplies from the beach to the dumps and for the subsequent issue to the divisions.

Tactical lessons learned were also new to the Central Pacific war. Instead of a small atoll, the battle had been one of movement on a sizable land mass, and it was further complicated by the numerous caves and the defensive systems they provided for the Japanese. The enemy had defended caves before, but never on such a large scale. On Saipan, these caves were both natural and man-made. Often natural vegetation gave them excellent camouflage. Some had steel doors which could be opened for an artillery piece or machine gun to fire, and then retreat behind the door before return fire could take effect. The flame-throwing tanks could reach many of these caves and so proved very useful. Unfortunately, their range was limited on Saipan, but this was later improved.

Thus it was that the hard experiences on Saipan led to a variety of changes which paid valuable dividends in saving American lives in the future Pacific campaigns. And the loss of the island was a strategic strike from which the Japanese never recovered, as the United States drove forward to ultimate victory.