How the Battle of Saipan Ended the Japanese Empire

Image Credit: U.S. Military
July 13, 2019 Topic: History Region: Asia Blog Brand: The Buzz Tags: Imperial JapanAmericaWorld War IIImperial Japanese NavyU.S. Navy

How the Battle of Saipan Ended the Japanese Empire

The tide was turned.

“Saipan combined everything that the Americans had learned to hate about fighting the Japanese,” wrote historian Brian Blodgett in his paper “The Invasion of Saipan.” “The island was comprised of varied landmasses with swamps, sugarcane fields, jungle-covered mountains, and steep ravines.”

Peering through his binoculars, Vice Adm. Chuichi Nagumo was in awe of the nearly 800 ships from Vice Adm. Raymond A. Spruance’s 5th Fleet. Just three years before he had led the carrier force at the surprise attack on Pearl Harbor that initiated hostilities between Japan and the United States. But this was no time to gloat over past victories. As he lowered his glasses, Nagumo realized that the Americans must be stopped here. If the invading forces captured Saipan, their Boeing B-29 Superfortress bombers could easily reach Japan itself.

Saipan, about 85 square miles in size, is the southernmost island in the Marianas chain. It was the next important step in the Allied planning to conquer Japan. One of Saipan’s dominating features is Mount Tapotchau, over 1,500 feet high, situated near the center of the island. Also, a ridge runs from the southern end all the way to Mount Marpi at the extreme northern tip. To make things worse, steep cliffs dominate the region and a plateau is located in the southern area.

(Originally Published May 29, 2019. This article originally appeared on the Warfare History Network.)

“Saipan combined everything that the Americans had learned to hate about fighting the Japanese,” wrote historian Brian Blodgett in his paper “The Invasion of Saipan.” “The island was comprised of varied landmasses with swamps, sugarcane fields, jungle-covered mountains, and steep ravines.”

American forces had their work cut out for them.

And the Japanese had not been idle. They had been fortifying the island’s defenses since the mid-1930s. The military had constructed airfields, barracks, radio direction finders, artillery positions, lookout stations, and ammunition dumps. On the southern tip of Saipan was Aslito Airfield, the major airstrip in the region. Another aerodrome was located at Charan Kanoa on the island’s southwest coast. Tanapag Harbor, on the western coast, near the town of Garapan, also served as a seaplane base. It was also used as a refueling stop and supply station for the Imperial Japanese Navy.

“The Fate of the Japanese Empire Depends on the Result of Your Operation”

Sharing command on Saipan with Nagumo was Lt. Gen. Yoshitsugu Saito. He was in charge of the Army contingent. Even the Japanese prime minister, Hideki Tojo, realized the importance of Saipan when he told Saito: “The fate of the Japanese Empire depends on the result of your operation.” Although in poor health, Saito accepted his fate. He knew it would be a struggle to the death.

Nagumo did not get along with his Army counterpart. Saito was becoming increasingly irritated by the Navy’s failure to eliminate the U.S. submarine threat and blamed Nagumo personally. One-third of all ships were lost to American subs prowling the waters near Saipan. These strained relations did not bode well for the impending battle. Nonetheless, the Japanese garrison on Saipan was prepared to die for the Emperor—and take as many American troops with them as possible. In spite of their differences, both Nagumo and Saito were optimistic. If they could hold the Americans at the beach and fight a delaying action, their massive combined fleet could reach Saipan in time, maul the American naval vessels covering the invasion area, and help Japanese land forces annihilate the invading armies.

Saito’s force defending Saipan consisted of the 31st Army, which included the 43rd Division and the 47th Independent Mixed Brigade. Admiral Nagumo had the 55th Naval Guard Force and the 1st Yokosuka Special Landing Force under his command. Although the U.S. Navy was sinking Japanese troop transports at an alarming rate, the army on Saipan was still formidable; some 30,000 troops were poised to do battle.

In addition, the island’s civilian population, which was a mixture of Japanese, Okinawans, Koreans, Formosans, and the native Chamorros and Kanakas, was pro-Japanese. The majority of the citizens of Saipan hated the Americans as much as the Japanese military, and believed them to be butchers and rapists.

Preliminary bombing of Saipan commenced on June 11. Over 200 bombers and fighters from Task Force 58 went virtually unchecked as they “plastered” Aslito Airfield and Garapan. As the U.S. aircraft casually flew away, leaving behind the burning wreckage of over 50 aircraft strewn about the airstrip, one disillusioned enemy observer later wrote in his diary: “Now begins our cave life.

16-Inch Shells Ripped Into the Landscape

As the Japanese were hurriedly preparing Saipan’s defenses, Spruance was busy as well. He had given the assignment of seizing Saipan to the crusty Marine Lt. Gen. Holland “Howlin’ Mad” Smith. Smith tapped the 2nd Marine Division of Tarawa fame led by Maj. Gen. Thomas E. “Terrible Tommy” Watson. He also selected the 4th Marine Division under Maj. Gen. Harry Schmidt and the U.S. Army’s 27th Infantry Division commanded by Maj. Gen. Ralph C. Smith. For additional punch, Smith had the U.S. Army’s XXIV Corps Artillery, headed by Brig. Gen. Arthur M. Harper. Most of the Leathernecks in both divisions had experienced combat on Guadalcanal, Tarawa, Kwajalein, or Eniwetok. On the other hand, the majority of the Army personnel had not experienced their first taste of war; however, that would soon change in the days to come.

On June 13, Vice Adm. Marc A. Mitscher’s battleships of Task Force 58 let loose an awesome barrage upon the island. Sixteen-inch shells from seven new battleships ripped into the landscape, reducing buildings and other structures to masses of smoldering rubble. For the next 10 hours the battlewagons fired more than 15,000 rounds of 16-inch and 5-inch shells. However, because the vessels were so far offshore, their bombardment did not do as much damage as first thought. The smokestack at the sugar mill at Charan Kanoa was left intact. During the fighting a few days later, an enemy forward observer climbed to the top and used it quite effectively.

The following day, the older, more experienced battlewagons, such as the Tennessee and California, let loose their pounding upon the Japanese. Accompanied by cruisers and destroyers, the armada commenced firing. However, two days of incessant bombing still did not silence many of the Japanese beach defenses, which were still operational when the assault troops hit the beach.

A Menacing Island Paradise

As the Navy belched round after round at the island, the Japanese initiated “A-Go,” a plan to halt the American advance in the Pacific. Admiral Soemu Toyoda’s Combined Fleet steamed toward Saipan to crush U.S. forces. “The fate of the Empire rests on this one battle,” remarked Toyoda.

In the predawn hours of June 15, the U.S. attacking force was poised a few miles off the beaches. Time-Life correspondent Robert Sherrod later wrote: “[Saipan] was a shadowy land mass, purple against the dim horizon. Set against the reddish tint of the morning sun, it seemed unbelievable that this island paradise could prove to be so menacing.”

Without warning, the massive flotilla offshore suddenly sprung to life with a thunderous barrage. At 0700 the firing ceased and 51 scout bombers and 54 torpedo bombers roared toward the beaches to further harass the defenders. This bombing and strafing run lasted for 30 minutes. As the planes streaked away, the ships once again commenced their deafening bombardment. With all the naval gunfire and air strikes, Saipan was barely visible from the transports amid the columns of thick, black smoke swirling upward.

After a feint in the north, the invasion force soon headed for the landing beaches located on the southwest coast. Covering a four-mile area, the 2nd Marine Division was on the left and the 4th Marine Division on the right flank. Several dozen LCI (Landing Craft, Infantry) gunboats fired rockets and strafed the shore with 20mm and 40mm guns. Following them were over a hundred amphibian tractors, or “amtracs,” equipped with 75mm howitzers and machine guns. Half the vehicles were U.S. Army and the remainder belonged to the Marines. Behind them rode the assault troops—about 700 regular amtracs—ready to hit the beach.

Punishing Fire Rained Down On the Marines

Japanese artillery shells soon sent huge geysers of water skyward. Marines ducked for cover as some of the enemy rounds began to find their mark. On Red Beach 2, Lt. Col. William K. Jones narrowly missed death. He was sitting on an ammunition crate when suddenly a shell burst overhead. At first Jones thought he was wounded when he saw blood on his hand. Looking around he also noticed a gaping hole in the side of the tractor near which he had just been standing. Turning to his right he saw where the blood had come from. Two Marines were bleeding profusely—both had been beheaded by the shell that had caused the hole in the vehicle.

To the south, on Green Beach, the 2nd and 8th Marine Regiments were also finding the going tough. Lieutenant Colonel Ray Murray, leading the 2nd Battalion, 6th Marines, soon fell from wounds. Also, Lt. Col. Jim Crowe, commanding officer of the 2nd Battalion, 8th Marines, was also a casualty when he was shot in the chest. As two medical personnel ran to assist Crowe, a mortar shell exploded nearby, killing both of them and wounding Crowe again.