BREACHING THE MARIANAS: The Battle for Saipan
by Captain John C. Chapin
U.S. Marine Corps Reserve (Ret)
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
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
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.