World War II: Battle of Saipan

US Marines
US Marines during the Battle of Saipan. (National Archives & Records Administration)

The Battle of Saipan was fought June 15 to July 9, 1944, during World War II (1939-1945) and saw Allied forces open a campaign in the Marianas. Landing on the island's west coast, American troops were able to push their way inland against fanatic Japanese resistance. At sea, the island's fate was sealed with the Japanese defeat at the Battle of the Philippine Sea on June 19-20.

Fighting on the island lasted several weeks as American forces overcame difficult terrain that included numerous cave systems and an enemy that was unwilling to surrender. As a result, almost the entire Japanese garrison was killed or committed ritual suicide. With the island's fall, the Allies commenced building airbases to facilitate B-29 Superfortress raids on the Japanese home islands.

Fast Facts: Battle of Saipan

  • Conflict: World War II (1939-1945)
  • Dates: June 15 to July 9, 1944
  • Armies & Commanders:
    • Allies
      • Vice Admiral Richmond Kelly Turner
      • Lieutenant General Holland Smith
      • Approx. 71,000 men
    • Japan
      • Lieutenant General Yoshitsugu Saito
      • Admiral Chuichi Nagumo
      • Approx. 31,000 men
  • Casualties:
    • Allies: 3,426 killed and missing, 10,364 wounded
    • Japanese: approx. 24,000 killed in action, 5,000 suicides


Having captured Guadalcanal in the Solomons, Tarawa in the Gilberts, and Kwajalein in the Marshalls, American forces continued their "island-hopping" campaign across the Pacific by planning attacks in the Marianas Islands for mid-1944. Comprised primarily of the islands of Saipan, Guam, and Tinian, the Marianas were coveted by the Allies as airfields there would place the home islands of Japan within range of bombers such as the B-29 Superfortress. In addition, their capture, along with securing Formosa (Taiwan), would effectively cut off Japanese forces to the south from Japan.

B-29 Superfortress over Japan. US Air Force

Assigned the task of taking Saipan, Marine Lieutenant General Holland Smith's V Amphibious Corps, comprised of the 2nd and 4th Marine Divisions and the 27th Infantry Division, departed Pearl Harbor on June 5, 1944, a day before Allied forces landed in Normandy half a world away. The naval component of the invasion force was led by Vice Admiral Richmond Kelly Turner. To protect the Turner and Smith's forces, Admiral Chester W. Nimitz, Commander-in-Chief of the US Pacific Fleet, dispatched Admiral Raymond Spruance's 5th US Fleet along with the carriers of Vice Admiral Marc Mitscher's Task Force 58.

Japanese Preparations

A Japanese possession since the end of World War I, Saipan had a civilian population of over 25,000 and was garrisoned by Lieutenant General Yoshitsugu Saito's 43rd Division as well as additional supporting troops. The island was also home to Admiral Chuichi Nagumo's headquarters for the Central Pacific Area Fleet. In planning for the island's defense, Saito had markers placed offshore to aid in ranging artillery as well as ensured that proper defensive emplacements and bunkers were built and manned. Though Saito prepared for an Allied attack, Japanese planners expected the next American move to come further south.

Fighting Begins

As a result, the Japanese were somewhat surprised when American ships appeared offshore and commenced a pre-invasion bombardment on June 13. Lasting two days and employing several battleships that had been damaged in the attack on Pearl Harbor, the bombardment ended as elements of the 2nd and 4th Marine Divisions moved forward at 7:00 AM on June 15. Supported by close-in naval gunfire, the Marines landed on Saipan's southwestern coast and took some losses to Japanese artillery. Battling their way ashore, the Marines secured a beachhead approximately six miles wide by half a mile deep by nightfall (Map).

Saipan landings, 1944
US Marines dig in on the beach at Saipan, 1944. Library of Congress

Grinding Down the Japanese

Repelling Japanese counterattacks that night, the Marines continued pushing inland the next day. On June 16, the 27th Division came ashore and began driving on Aslito Airfield. Continuing his tactic of counterattacking after dark, Saito was unable to push the US Army troops back and soon was compelled to abandon the airfield. As fighting raged ashore, Admiral Soemu Toyoda, Commander-in-Chief of the Combined Fleet, commenced Operation A-Go and launched a large attack on US naval forces in the Marianas. Blocked by Spruance and Mitscher, he was badly defeated on June 19-20 at the Battle of the Philippine Sea.

Japanese POW, Saipan
Surrendering Japanese soldier emerges from cave on island of Saipan, 1944. Library of Congress

This action at sea effectively sealed Saito and Nagumo's fate on Saipan, as there was no longer any hope of relief or resupply. Forming his men in a strong defensive line around Mount Tapotchau, Saito conducted an effective defense designed to maximize American losses. This saw the Japanese use the terrain to great advantage including fortifying the island's numerous caves.

Moving slowly, American troops utilized flamethrowers and explosives to expel the Japanese from these positions. Frustrated by a lack of progress by the 27th Infantry Division, Smith sacked its commander, Major General Ralph Smith, on June 24. This engendered controversy as Holland Smith was a Marine and Ralph Smith was US Army. In addition, the former failed to scout the terrain through which the 27th was fighting and was unaware of its severe and difficult nature.

As US forces pushed back the Japanese, the actions of Private First Class Guy Gabaldon came to the fore. A Mexican-American from Los Angeles, Gabaldon had been partly raised by a Japanese family and spoke the language. Approaching Japanese positions, he was effective in convincing enemy troops to surrender. Ultimately capturing over 1,000 Japanese, he was awarded the Navy Cross for his actions.


With the battle turning against the defenders, Emperor Hirohito became concerned about the propaganda damage of Japanese civilians surrendering to the Americans. To counteract this, he issued a decree stating that Japanese civilians that committed suicide would enjoy an enhanced spiritual status in the afterlife. While this message was transmitted on July 1, Saito had begun arming civilians with whatever weapons could be procured, including spears.

Increasingly driven towards the island's northern end, Saito prepared to make a final banzai attack. Surging forward shortly after dawn on July 7, over 3,000 Japanese, including wounded, struck the 1st and 2nd Battalions of the 105th Infantry Regiment. Nearly overwhelming the American lines, the attack lasted over fifteen hours and decimated the two battalions. Reinforcing the front, American forces succeeded in turning back the assault and the few Japanese survivors retreated north.

As the Marines and Army forces eliminated the final Japanese resistance, Turner declared the island secured on July 9. The next morning, Saito, already wounded, committed suicide rather than surrender. He was preceded in this act by Nagumo, who committed suicide in the battle's final days. Though American forces actively encouraged the surrender of Saipan's civilians, thousands heeded the emperor's call to kill themselves, with many jumping from the island's high cliffs.


Though mopping up operations continued for a few days, the Battle of Saipan was effectively over. In the fighting, American forces sustained 3,426 killed and 10,364 wounded. Japanese losses were approximately 29,000 killed (in action and suicides) and 921 captured. In addition, over 20,000 civilians were killed (in action and suicides). The American victory at Saipan was quickly followed by successful landings on Guam (July 21) and Tinian (July 24). With Saipan secured, American forces quickly worked to improve the island's airfields and, within four months, the first B-29 raid was conducted against Tokyo.

Due to the island's strategic position, one Japanese admiral later commented that "Our war was lost with the loss of Saipan." The defeat also led to changes in the Japanese government as Prime Minister General Hideki Tojo was compelled to resign. As accurate news of the island's defense reached the Japanese public, it was devastated to learn of the mass suicides by the civilian population, which were interpreted as a sign of defeat rather than spiritual enhancement.

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Hickman, Kennedy. "World War II: Battle of Saipan." ThoughtCo, Jul. 31, 2021, Hickman, Kennedy. (2021, July 31). World War II: Battle of Saipan. Retrieved from Hickman, Kennedy. "World War II: Battle of Saipan." ThoughtCo. (accessed March 26, 2023).