The Americans needed the airbases present in the Marianas
in order to bring the Home Islands of Japan within range
of Americas newest strategic bomber, the B-29
Super-Fortress.  Once secured, the US would be able to 
apply its strategic bombing doctrine against the
industries of Japan as had been done with those of
Germany, destroying her ability to produce the weapons
of war and hopefully shorten the war.

The Japanese government under Premier Tojo, were all
too aware of Saipans importance and had designated it
as part of their "Absolute Zone of National Defense".
Admiral Toyoda, the commander in chief of the recently
re-structured Combined Fleet, was charged with defending
this zone by bringing the American fleet to decisive
battle. Toyoda knew that, while still powerful, his
Combined Fleet was no longer capable of defeating the
vastly augmented American fleet single-handedly. Thus,
he devised plan A-GO, the main feature of which would
be the mass use of land based naval squadrons to soften
up the encroaching American carrier fleet and par down
its numbers to a level in which Toyodas fleet could
handle.

The resulting Battle of the Philippine sea would expose
the folly of "A-GO" Japanese aircraft losses would total
319 vs. only 23 on the American side. The inexperienced
and poorly trained Japanese pilots proved to be no match
for the veteran American pilots, now flying in aircraft
largely superior to those being flown by Japan.

Operation A-GO ended in complete failure. Japan's
carrier force was completely demolished as an
operational entity.  Never again would the fleet carriers
sail as a force of battle and the survivors would end out
their service lives as floating decoys to draw away the
USN's carrier strength during the Battle of Leyte Gulf.

Saipan itself would fall by July 6th, causing the downfall
of Prime Minister Tojo's government and serving notice to
the rest of Japan that soon, American airpower would be
seen over their airspace.

