D-Day in the Pacific | The Invasion of Saipan, 1944

Having successfully pushed through the Gilbert and Marshall Islands, the Allies now set their sights on the Marianas: Saipan, Guam, Tinian, Rota, and Pagan. From this strategic point in the Pacific, they would be able to bomb the Japanese mainland. This massive operation involved thousands of troops from all branches of the military and an overwhelming number of ships, vehicles, and weapons. 

The plan called for bypassing a full assault on Rota and Pagan, instead aiming at Saipan as its primary goal. Guam and Tinian were secondary targets. To invade Saipan would be a significant challenge for the Pacific Fleet since Japan regarded it as part of her homeland as well as integral to her inner defense perimeter.

Beginning June 11, 1944, American aircraft carriers carried out heaving bombing of airfields in the Marianas. Battleships also bombarded the islands.¹ 

Source: Wikimedia Commons

Today's date marks the anniversary of Saipan D-day in 1944. Sixty-four Land Ship Tanks (LSTs), some of which my dad, Frank Dolan, had worked on earlier at Pearl Harbor, landed U.S. Marines on 8 different beaches on a 4-mile wide front. Twenty-four gunboats offered some close protection for the landing force while battleships, cruisers, and destroyers pounded beach defenses. Eight thousand Marines got ashore within the first 20 minutes, with 12,000 more to follow throughout the day along with 1,400 amphibious tanks.

U.S. Marines in the first wave on the Saipan beaches
Source: National Archives

Awaiting the Marines were over 32,000 Japanese troops, more than twice the number anticipated. More than 2,000 Marines were killed on the beaches before the beachhead was secured 2 days later. It would be a long and hard-fought battle to take the island.

As the Marines fought off counter-attacks, the Japanese decided that the best way to support the island’s defenders was to attack the Americans at sea. This resulted in the Battle of the Philippine Sea, June 19, 1944. The attack proved to be a disaster for the Japanese as they lost 3 aircraft carriers along with many planes. The loss of their carriers meant that the Japanese force on Saipan could not be resupplied or reinforced, and they were effectively cut off.

Troops make their way to the beach from LSTs, some of which

were readied and repaired by Dad's ship, USS Hector

Source: National Archives

By the 22nd, Marines had pushed across the island, cutting the defending force in two. Realizing that he would not be reinforced, Japanese Gen. Yoshitsugu Saito ordered his troops to fight the last man. The Japanese held a final defensive line around Mount Tapotchau, a series of caves in the mountainous center of Saipan. In their assault, the Americans were forced to use flamethrowers to kill or drive the enemy from their underground hiding places.

In a climatic enemy attack on July 7, over 3,000 Japanese, including wounded and some civilians, struck the U.S. Army's position in a desperate charge. Nearly overwhelming their lines in an attack which lasted over 15 hours, the American soldiers bravely fought back. With reinforcements, the army succeeded in turning back the assault with very few Japanese survivors.

Throughout the invasion, Japanese defenders were tenacious, completely willing to fight to the death. Indeed, more than 30,000 had to be killed before Saipan was taken by July 7th.² For the Americans, over 3,400 of the 67,451 troops who participated were killed or reported missing.

The American victory at Saipan was quickly followed by successful landings on Guam on July 21st, and Tinian on July 24th, although there was heavy fighting in the battles for both islands. With the Marianas secured, the Americans quickly developed air bases for long range B-29 bombers that could reach the Japanese mainland, helping to hasten the end of the war.³

¹ The battleship, USS Tennessee, was damaged by artillery fire from Tinian. Eight men were killed and 26 wounded. Despite the damage and loss of personnel, Tennessee delivered fire on a Japanese counterattack near Agingan Point on Saipan before leaving for emergency repairs. The next day, the ship returned to Saipan channel to provide supporting fire to assist U.S. Marines in consolidating their beachhead. On the 22nd, Tennessee sailed for Eniwetok where Dad's repair ship, Hector, repaired her battle damage. On June 14, another battleship, the USS California, was hit by a shell from a Japanese shore battery on Saipan, killing 1 man and wounding 9. Dad's ship repaired her damage at Eniwetok as well.

² Tragically, more than 20,000 civilians also were killed, many of these jumping from cliffs to their deaths. Despite efforts by U.S. troops to persuade them to surrender they were convinced that untold horrors awaited them if they fell into the hands of the Americans.

³On November 24, 1944, U.S. B-29 bombers attacked the Nakajima aircraft factory northwest of Tokyo. The high-altitude mission marked the first bombing raid of Japan from the Mariana Islands.

Sources: The Two-Ocean War, Samuel Eliot Morrison; Dictionary of American Naval Fighting Ships: USS Hector III (AR-7); USS Hector AR7- Ship's Log (WWII)