In its geographical scope, speed, operational agility and, above all, strategic effectiveness,
carrier-led warfare was revolutionary. Scarcely less novel was the demonstration under
fire of the effectiveness of the US Marine Corps’ new doctrine of amphibious assault.
The marines’ learning curve was expensive in blood, but it was steep and rapid.
The fast-forward movement of the American fleet, led by its carrier task forces, was,
of course, an invitation to the Imperial Japanese Navy to come out and fight. This reality
had a parallel in the war in Europe. Daylight bombing by the USAAF’s Eighth Air Force
had the effect of all but obliging a rapidly declining Luftwaffe air defence force to take
to the skies. Aloft, by March 1944 at least, it could be shot down in droves by the Allies’
new escort fighters. The Japanese impotently witnessed the demolition of their theory
and practice of extended perimeter defence of their empire. They knew that they had to
stop the US Navy somewhere, or eventually it would appear in Tokyo Bay. But where
should decisive battle be offered? Strategic geography provided just one answer: the
Marianas. These islands were the innermost elements in the entire maritime defence
perimeter. From them, the US Navy could reach directly for the Japanese Home Islands,
via the Bonins – including a tiny volcanic island called Iwo Jima – or westwards to the
Philippines or Taiwan. Also, from air bases in the Marianas, particularly on the larger
islands of Guam, Tinian and Saipan, America’s land-based heavy bombers would be
within range of Japan. Take the Marianas, therefore, and the new B-29s would have no
need of bases in China.
Victory in the Marianas
US Army and Marine units stormed ashore on Saipan on 15 June 1944, opening a
campaign that was to last until 13 July and cost 14,000 casualties. The climactic
encounter at sea that both sides sought, albeit cautiously (especially on the American
side, strangely), occurred on 19–20 July. As at the Coral Sea and Midway, the Battle of
the Philippine Sea was entirely an aerial encounter. The only exception was provided by
inept Japanese submarine forays which cost an incredible seventeen boats for no return.
For good reason, American pilots called the battle off Saipan ‘the Marianas Turkey
Shoot’. Japanese carrier aircraft made 328 sorties and managed to lose 243 planes. The
island-based First Air Fleet lost a further fifty. American losses numbered only twenty
aircraft from enemy action. There was nothing mysterious about the crushing American
victory. By June 1944, American carrier air power enjoyed decisive advantages in the
form of new models, airborne radar and, more important still, pilots who were tactically
superior to their Japanese foes. The result was a massacre that marked the effective end
of Japan’s once world-leading carrier air power. However, because of poor intelligence
and overcautious leadership by Admiral Raymond A. Spruance, commander of the US
Navy’s Fifth Fleet, the Japanese carriers and other surface vessels were not engaged by
American aircraft. The US Navy lost more planes and pilots in an ill-judged, heroic, yet
futile effort to find and engage the Japanese carriers than it did in the battle. The Pacific
at night is vast and lonely when you are running low on fuel and you cannot be sure of
the exact location of your mobile home. The Imperial Japanese Navy lived to fight again,
but henceforth it would have to fight bereft of an offensive, or defensive, air arm.
The Japanese had hoped to deliver a painful, if not necessarily disabling, blow to the
principal American carrier force off Saipan. Instead, they had hastened their own demise.
World War II in Asia–Pacific, II 177