Marines Triumph in Saipan

After losing vast territories to the Japanese Empire in 1942, the Allies were advancing in the Pacific by 1944. The U.S. Marines had taken both the Gilbert and Marshall Islands by 1944. After the fall of those territories, the Mariana Islands became the next stepping stone for the Marines' advances in the Pacific War.

The Marianas consist of Saipan, Guam and Tinian. Saipan is an island with sandy beaches on its western coastline, and has more mountainous terrain further inland. In the centre of the island is Mount Tapochau which rises some 1,560 feet.

This was a part of the Japanese Empire that included Aslito airfield, which was one of their more essential air bases between Japan and Truk, and another air strip in Charan Kanoa. In the northern end of Saipan they were also constructing another airfield at Marpi Point.

Taking Saipan would, therefore, provide the U.S. Air Force with further airfields from which to step up their bombing campaigns. The airfields in Saipan would put their B-29 aircraft within range of Japan, and other home islands, for large-scale air raids of military and industrial targets. In addition, capturing the Marianas would also cut off Japan's southern forces.

Consequently, the Allies blockaded Saipan with their submarines before June 1944. This ensured that large quantities of construction materials, required for coastal defenses, did not reach Saipan. Japan's coastal defenses in Saipan remained incomplete, but still included eight six guns, nine 140mm guns, eight 120mm dual-purpose guns, four 200mm mortars and a couple of dozen concrete blockhouses and pillboxes.

The Japanese army had a garrison of about 32,000 troops for the Battle of Saipan in June. This garrison was twice as large as the Allied estimates expected. However, the submarine blockade also limited supplies for the Japanese garrison in Saipan.

The U.S. Marines sent to invade Saipan consisted of the 2nd and 4th Marine Divisions under General Smith. They were also reinforced with the 27th Infantry Division. In total they had about 71,000 troops for the Battle of Saipan.

The Battle of Saipan began with a preliminary naval bombardment. U.S. carrier aircraft shot down Japanese planes over the Marianas, and aerial bombardments targeting their airfields wiped out potential Japanese air support. U.S. surface fleet warships were too far from their targets to have any notable impact. Thousands of shells rained down on Saipan during the bombardment, which provided their underwater demolition teams with cover to pinpoint paths through the reefs for their landing crafts.

On 15 June the first Marines swept ashore Saipan's beaches. Japan's General Saito correctly anticipated that the Marines would land on the western beaches of Saipan around Charan Kanoa. The Marines organized the landings into four waves supported by 96 amphibious landing vehicles and 64 landing ship tanks. LCI gunboats also provided close fire support for the Marines as they landed. Japanese artillery shells rained down on the beaches as the Marines poured ashore. Their artillery positions effectively wiped out U.S. amphibious tanks which bogged down in the loose sand and holes along the beaches.

Japanese pillboxes remained largely intact after the naval bombardment, and pillbox fire effectively split the beachhead. Upon landing the Marines did not effectively link the beachhead, and were left vulnerable to Japanese counters. However, as they counter-attacked along both beaches simultaneously they did not exploit the vulnerability. The Marines still drove the Japanese out, and held their positions on the beaches.

As the Marines clung to the beaches their numbers increased, and they doubled the size of the beachhead. From there they advanced towards Aslito airfield. The 165 Regiment reached and secured the airfield. The airfield was soon repaired for U.S. aircraft landings. Having lost the beaches and airfield, the Japanese troops retreated to set up new lines along Mount Tapochau.

The IJN (Imperial Japanese Navy) had planned to defeat Task Force 58 in the surrounding seas with a fleet of aircraft carriers, and further air support from the Marianas. However, having lost many of their land-based aircraft, the Japanese aircraft carriers did not have much in the way of additional air support. Nevertheless, they still launched waves of aircraft towards the U.S. carriers during the Battle of the Philippine Sea in which U.S. F6F aircraf shot Japanese planes out of the sky in numbers.

U.S. submarines wiped out two of the Japanese aircraft carriers during the battle. Follow-up strikes from U.S. aircraft rediscovered the remaining Japanese carriers' position. They finished off the Hiyo before the Japanese fleet withdrew. With the Japanese naval fleet defeated at the Battle of the Philippine Sea, Japan's troops in Saipan could not be reinforced or resupplied. Having also established a beachhead, victory was all but assured for the U.S. Marines.

Yet they still had much of Saipan to capture. The Marines occupied territory in the south, but further northwards the Japanese troops had established new positions. Reinforcements from the 27th Division arrived in the south of Saipan near to Agingan Point shortly before the Marines captured Aslito airfield.

With three U.S. divisions in Saipan Smith gave the orders for a general northward advance. For the advance the 2nd Marine Division moved up the western coastline of Saipan, and the 4th Marine Division along the flatter eastern flank of Saipan. In between them the 27th Infantry Division moved through the center up Mount Tapochau.

The Japanese troops slowed the 27th Division's advance up Mount Tapochau. Marines advanced through a valley where the Japanese held the high ground on both sides. Along the cliffs they had placed artillery, mortar and machine gun positions from which to wipe out U.S. troops.

The Marines advanced up the coasts more quickly. The 4th Marine Division approached the village of Garapan, or what was left of it, on the western coastline. Along the eastern shorelines the 4th Marine Division took much of Saipan's eastern peninsula. They continued to advance towards Tanapag Harbor. 

With further support from the Marines, Mount Tapochau was gradually cleared. In July, the U.S. troops secured the mountain, took Garapan and advanced northwards towards Marpi Point. In the south, about 500 Japanese soldiers raided Aslito airfield; and wiped out a few U.S. infantry battalions before running into a couple of Marine regiments.The Marines declared Saipan secured by 9 July.

The Battle of Saipan ended in triumph for the U.S. Marines and Army. They had lost 3,426 troops and captured 1,780 Japanese soldiers. They had taken a vital outpost of the empire that soon became a launchpad for a number of bombing raids over the Japanese home islands. Thereafter, U.S. aircraft ravaged Japanese military and industrial targets. They also established a base in Saipan with an oil farm that included 100,000 barrels of fuel.

Although the Mariana Campaign was not entirely won after the Battle of Saipan. The Marines invaded both Tinian and Guam soon after their victory at Saipan. They won both battles to wrap up the campaign in the Marianas.

The Battle of Saipan left the Japanese Empire on the verge of defeat. After the loss of the Marianas, Tojo and his cabinet resigned. The Japanese military began to concede that they were losing the war, but were not about to surrender. The Pacific War continued into 1945 as the Marines took both Iwo Jima and Okinawa. The Russians also invaded, and swept through, areas of Manchuria before Japan surrendered.

Battles of the Pacific War 1941 - 1945
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On the 7th of December, 1941 hundreds of
Japanese aircraft took off from a group of
aircraft carriers. Their target was Pearl
Harbour in Oahu, Hawaii which was home of
the U.S. Pacific Fleet. The Pacific War began
here, and for almost four years the United
States and their allies remained at war with
the Japanese Empire. During this period the
war in the Pacific engulfed much of Asia,
from the borders of India to the Indonesian
Islands on the outskirts of Australia.

This is a concise, yet detailed, historical
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some of the largest battles in the Pacific
Theatre. Famous 20th century battles in the
vast seas, islands and jungles of the Pacific
region, beginning with the devastating
Japanese airstrike at Pearl Harbour. A tale
of epic confrontations, Battles of the Pacific
War 1941 - 1945 recalls where, when and
how the Pacific War was won and lost
within the battlefields of the Pacific.
Battling for Saipan
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