As allied troops crossed the English Channel to invade northern France on June 6, 1944, 600 U.S. Navy ships were converging on the Mariana Islands, Japanese territory only 1,200 miles from the homeland.
Two and a half years after being battered at Pearl Harbor, the United States had the power to conduct two huge invasions simultaneously.
In 1942, the first year of the war, the Japanese and the U.S. traded losses in a number of naval battles. At one point, the United States had only one large operational carrier in the Pacific. United States shipbuilding companies made good these losses. Japan could not.
In 1943, the Japanese did not commit their battered carrier force in any large operations. However, experienced Japanese naval aviators were sent to bases in the South Pacific and many were killed in their efforts to challenge American and Australian advances in the area.
By November 1943, the United States possessed a number of new carriers and other warships. The Navy initiated the Central Pacific Campaign with the invasion of the Gilbert Islands and then, in the spring of 1944, moved west into the Marshall Islands.
Before invading an island, a U.S. carrier task force would isolate it by conducting raids against any nearby Japanese bases that could offer the enemy support. The Navy force heading to the Mariana Islands in June 1944 included over a dozen new aircraft carriers. As they softened the islands with air attacks and bombardment, U.S. submarines discovered a powerful Japanese carrier force moving towards the Marianas. After a year and a half since their last major clash with the Navy, the Japanese carrier force was finally en route to join battle. If the Mariana Islands were lost, large U.S. bombers would be within range of the Japanese homeland.
The defenders of Saipan contested the June 15 landings ferociously. In the first two days, the Japanese launched a desperate night-time attack with tanks to drive the Americans into the sea. This attack was broken by American tanks, artillery and naval flares and gunfire.
At sea, the U.S. did not initially seek out the approaching Japanese force. The Navy could afford to wait for the enemy to come. Besides hundreds of carrier aircraft, the U.S. had developed an effective radar air control system and supporting warships bristled with anti-aircraft weapons.
The U.S. also had a secret weapon – 5-foot anti-aircraft shells with proximity fuses which detonated when the shell was near aircraft.
The Japanese struck on June 19 with waves of aircraft heading to the American fleet. U.S. radar operators vectored the new Navy Hellcat fighters to the Japanese planes. The Japanese squadrons were shredded as they approached the fleet. Their pilots no longer had the experience they possessed earlier in the war and their aircraft were out-classed by these powerful new American fighters.
The few Japanese that made it near the American fleet were decimated by anti-aircraft fire from the carriers and their escorting warships. No major damage was inflicted upon American ships.
American submarines had stalked the Japanese attack force and sunk two of their aircraft carriers during the battle. A third Japanese carrier was destroyed by Navy fliers the next day and others were badly damaged. More importantly, the Japanese navy had lost most of its capable pilots. What was left of their carrier force was never a major threat again.
On Saipan, the battle wound up in a final orgy of violence in early July. Just before sunrise, the cornered Japanese launched the largest Banzai attack of the war. Some were armed only with spears. By the end of the day, over 4,000 Japanese bodies were bulldozed into a mass grave. Thousands of other Japanese troops committed suicide. Hundreds of civilians – fearing the Americans would torture or kill them – jumped off cliffs with their children.
By early August, Tinian and Guam were secured and the airbases for the new B-29 heavy bombers were being constructed.
The battle for the Marianas Islands gutted the once-proud Japanese carrier force. In later battles, the desperate Japanese initiated kamikaze attacks, which did a lot of damage to U.S. ships but did not change the tide of the war.
Bombing raids from the Mariana Islands burned major Japanese cities to the ground in 1945, culminating in the use of two atomic bombs in August.
The American victory in the Marianas marked the beginning of the end of the Empire of Japan.
Thomas R. Williamson is an attorney in Durango with a longterm interest in World War II history. Reach him at firstname.lastname@example.org.