War in the Pacific National Historical Park ⓘ

The Imperial Japanese conquest of Guam began on December 8, 1941, just hours after the bombing of Pearl Harbor.

At 8:27 a.m., while people were in church celebrating Gipot Santa Maria (Feast of the Immaculate Conception), nine Japanese planes appeared over the village of Sumai . They bombed the Pan American buildings and the Standard Oil fuel tanks outside of town. Two CHamoru men employed at the Pam American hotel were killed in the attack. The planes also sunk the USS Penguin (AM-33), the largest ship on Guam, and strafed Piti, Hagåtña and other major population centers.

Unable to defend their homes, residents of Sumai, Piti and Hagåtña fled to the bundåk (jungle), liyang (caves), and ranches in the hills for safety.

The planes returned the following day, destroying radio towers and military facilities. Then, during the early hours of December 10, two groups of Japanese soldiers began the invasion. Roughly 400 men from a special Japanese naval landing party of the 5th Defense Force started landing at Dungca's Beach in Agana Bay, just outside the capital city of Hagåtña. The South Seas Detachment, a Japanese army unit with 5,500-man, landed on near Aporguan, Tumon, Togcha, and Agat.

Guam was poorly prepared for the invasion. The island’s entire military force consisted of 274 U.S. Navy personnel, more than half of them non-combative personnel; 153 Marines; and about 120 Insular Force Guards with minimal military training. The garrison was armed with three machines guns, four Thompson submachine guns, six Browning automatic pistols, fifty .30 caliber pistols, a dozen .22 caliber regulation rifles, and eighty-five Springfield rifles labelled: Do not shoot. For training only .

Captain George J. McMillin, the island’s governor, sent most of the Marines to defend the Orote peninsula. Three platoons of the Insular Force Guard (roughly 85 men) were assigned to defend Hagåtña. The Insular Guard made a valiant attempt to stop the Japanese advance at the Plaza de Espana. They managed to drive the Japanese soldiers back twice but were soon overwhelmed. The battle lasted less than an hour.

By 5:45 a.m., McMillin realized that "the situation was simply hopeless," and began to surrender his post and the island. He signed the letter of surrender between 6:00 and 7:00 and the Japanese flag was raised over the governor's mansion.

For the next 32 months, Guam was Japanese-occupied territory. It was one of only four places in the United States occupied by enemy forces during World War II.

After Captain George McMillin surrendered to the Japanese Imperial Army , Guam spent two and a half years under Imperial Japanese control. Caught in a war they didn't start, the CHamoru endured a harsh military occupation from December 10, 1941 until July 21, 1944.

For the first few months, the island the Imperial Japanese Army controlled the island. The civilian affairs section of the Imperial Japanese Army (Minseisho) handled the civil government. The 6,000 Japanese troops on the island stayed in public buildings, private homes, and even the cathedral in Hagåtña (Agana).

The island was renamed Omiya Jima (Great Shrine Island) and the Japanese yen became the currency. Japanese soldiers required the CHamoru to learn the Japanese custom of bowing as a sign of respect. Signs were posted on public buildings throughout the island with the order "You must stop here and bow to us." Failure to bow, bowing too low, or not low enough was punishable by slapping, kicking, or hitting.

Japanese officials required residents to have a pass from Japanese officials in order to move about the island. CHamoru referred to this pass, a strip of cloth identifying the wearer in Japanese, as lisiensan ga'lago or dog tag.

The Minseisho confiscated cars, radios, and cameras and required a strict 10:00 p.m. to 4:00 a.m. curfew. Food was rationed until supplies became exhausted. CHamoru suspected of hiding family members wanted by the Japanese or helping the Americans were harassed, beaten, tortured, and even executed. The Japanese Army evacuated the village of Sumai and turned it into a Japanese garrison. Five CHamoru women were raped during the takeover.

By mid-January 1942, Guam was under Japanese control, and the Imperial Japanese Army troops departed. The Keibitai , a Japanese naval militia with less than 500 soldiers, took charge of the island. The Navy’s Department of Civil Administration ( Minseibu ) was in charge of the day-to-day administration of the island.

While Guam remained under martial law, life under the Minseibu was relatively calm as long as the CHamoru obeyed the Japanese officials. People remained on their farms and traded for products they needed. They took attended church, Japanese movies, sports competitions, and other social activities.

Mass meetings were held in Hagåtña to reinforce the Nippon Seishen (spirit of Japan). Military parades celebrated Japanese victories in the Pacific and Asia. A popular float showed a young boy dressed in an Imperial Japanese Army uniform aiming a display rifle at a child dressed in an American military uniform.

The Minseibu reopened public schools. CHamoru children and adults were required to learn the Japanese language and customs and not allowed to speak English or CHamoru. Despite their best efforts, the Japanese education programs were not popular. The Japanese school system never had more than 600 students.

As WWII dragged on, the situation in Guam changed dramatically. In 1943, the United States launched twin offensives. By the middle of the year, Japanese forces found themselves on the defensive.

The Imperial High Command declared that the Marianas, including Guam, were Japan's final line of defense and must be held at all costs. This triggered a rapid build-up of military personnel and defenses on Guam. In early 1944, 18,500 troops arrived in Guam. The Imperial Japanese Army took control of the island.

The army closed schools and churches. Other social activities were forbidden. Civilian women and children were forced to work long hours in the fields, growing food for the Japanese Army. Japanese soldiers forced CHamoru men to build airstrips and defense installations. Laboring at bayonet point, the Chamoru were mistreated and, in some cases, executed after completing defense installations. Most of the island's food supply was seized by the army, and the CHamoru were reduced to subsistence rations.

As their situation became more desperate, the Japanese troops became more brutal. Dozens of CHamoru were beaten, beheaded, or raped in the final days of the Japanese occupation. Massacres took place at Fena, Tinta, Faha, and Yigo.

On July 10, 1944 , Takashina ordered approximately 18,000 people, nearly the entire civilian population of Guam, to relocated to concentration camps in the jungles in the interior of the island. Manenggon was the largest of the camps. Most CHamoru spent the Battle of Guam in the concentration camps. Troops from the 77th Division reached Manenggon on July 31, killing the Japanese guards who didn't run away, and helping the CHamoru to return to what was left of their villages.

In late 1943, Admiral Chester W. Nimitz proposed a plan to capture the Mariana Islands. Capturing Guam, Saipan and Tinian would give the United States airfields that were within the range of the new B-29 bombers. This would allow America to bomb the Japanese home islands. The code name of the Marianas operation was "Forager."

For two weeks leading up to the invasion, the United States bombed the island. Battleships hurled 836 sixteen-inch rounds and 5,422 fourteen-inch shells. Cruisers fired 3,862 eight-inch and 2,430 six-inch rounds. Destroyers fired 16,214 five-inch shells.

While the bombardment battered the coast, the American Underwater Demolition Teams (UDTs) blew gaps in the rugged coral reefs surrounding the island. Destroying obstacles and mines, this created a route to shore for landing vehicles.

The Battle of Guam began on the morning of July 21, 1944, W Day for Guam. While a simultaneous attack launched five miles south at Hågat, the Third Marine Division, led by Major General Allen Turnage, landed on Assan (Asan) Beach .

Under the protection of heavy artillery from gunboats, the Marines were brought to shore in waves of armored Landing Vehicles and DUKWs. They landed on the beach in four groups and advanced to capture the cliffs before the Japanese could recover from the bombardment.

In three days, the Third Marine Division seized Assan and Adelup Point, captured Chorito Cliff and Bundschu Ridge, and secured the northern beachhead.

Five miles to the south, the 1st Provisional Marine Brigade under the command of Brigadier General Lemuel Shepherd landed at Hågat (Agat) Beach . The area was strategically chosen to help secure the Orote Peninsula to the north—home to a strategic airfield and the entrance to Apra Harbor.

In their way were heavy Japanese fortifications. A well-hidden concrete blockhouse at the tip of Ga’an Point, missed by reconnaissance planes before the battle, remained intact. It housed a 74mm gun and a 37mm gun, which fired on the first wave of Marines as their landing vehicles reached the shore. Seventy-five Marines were killed before the blockhouse was overrun.

The 305th Infantry Regiment of the U.S. Army’s 77th Infantry Division followed the Marines ashore . Due to a shortage of LVTs, the soldiers, carrying their weapons, ammunition, and equipment, were dumped in chest-high water and had to wade hundreds of yards to shore.

For the next several days, U.S. troops advanced during the day, then fended off Japanese counterattacks at night. Despite fierce resistance and a banzai attack on the night of July 21-22, U.S. troops captured Mount Alifan and secured the beachhead by July 24.

While American forces had secured the beachheads at Assan and Hågat by July 24, 1944, the fight for Guam was far from over. The beachheads were narrow, isolated strips of land surrounded by well-fortified hills and mountains still controlled by the Japanese. To join their position, the U.S. needed to secure the line of peaks stretching from Adelup Point in the east to Måkpo Point in the west. This would connect the two beachheads and allow American troops access to the rest of the island. However, they first needed to capture the Japanese stronghold on Fonte Plateau , which overlooked Assan Beach.

The Third Marine Division launched their attack on Fonte on the morning of July 25. By the end of the day, most of the battalions had reached the critical Mt. Tenjo Road, which crossed the high ground framing the beachheads.

As the Americans launched their assault, Lieutenant General Takeshi Takashina, commander of the Japanese forces on Guam, planned a major counterattack. He mustered more than 5,000 soldiers, the majority of his remaining forces in southwest Guam, on Fonte Plateau. His plan was to surge down the slopes surrounding the Assan beachhead and push the Americans to the edge of the water.

At 3:00 am, Japanese troops poured down the slopes from Fonte Plateau in a forward moving, last-ditch effort, to give their all in a banzai attack. Shouting, “Wake up American and die!” the Japanese charged towards the American tanks, artillery, and ammunition dumps. The Japanese launched seven consecutive waves of counterattacks before dawn on July 26. While they bent, the Third Marines did not break. Not only did the Japanese fail to break the American line, but they also suffered tremendous casualties. 3,200 of the best remaining Japanese soldiers on Guam died during the banzai.

After spending July 26 reorganizing and recovering from the night’s attack, the Marines renewed their assault on Fonte Plateau on July 27. By July 29, Fonte was in American hands. To the west, the 9th Marines made contact with a company of the 307th Infantry Regiment at Mt. Tenjo, securing the two beachheads.

While the Third Marine Division worked on securing the high ground overlooking the beachheads, the First Provisional Marine Brigade attacked Orote Peninsula, the strip of land jutting out into the ocean between the two beachheads. Home of the Orote airfield and an Imperial Japanese Army garrison, the peninsula was well-defended. The Japanese had constructed an elaborate interlocking system of pillboxes, strongpoints, and trenches.

Starting on July 25, the Marines fought their way through the swamps and thick jungle, forcing the Japanese defenders to the tip of the peninsula. On the afternoon of July 25, Japanese Commander Asaichi Tamai tried to evacuate his troops by barge across Apra Harbor in broad daylight. U.S. artillery and air strikes sank the barges.

His next plan was a frontal assault of the First Provisional Marine Brigade’s lines. Shortly before the banzai attack on the Third Marine Division began, the Orote defenders stormed out of the mangrove swamp at the Americans. Despite fierce fighting all night long, the Japanese troops were not able to break the American lines.

The First Provisional Marine Brigade continued their advance through the dense mangroves and swamps the following morning. They captured the former Marine Barracks and the village of Sumai on July 28. The following morning, after a furious barrage of artillery and airstrikes, the Marines captured the Orote airfield, and the peninsula was declared secure. Phase 1 of the liberation of Guam was complete.

After Takashina's death on July 28, General Hideyoshi Obata assumed command of the remaining 6000 Japanese soldiers on Guam. He withdrew his forces to the north of Guam and established his final defensive position in the Mount Mataguac-Mount Santa Rosa area.

General Roy Geiger, commander of the American forces on Guam, allowed his tired troops to rest for a few days. They started marching north on July 31. By August 6, the defense line that Obata had set across Guam had been shattered and overrun.

The final battle for Guam began at noon on August 7. The 77th Infantry Division captured Yigu (Yigo) on August 7. On August 8, they surrounded and secured the mountain, but only 600 bodies were found after the two-day fight. Significant numbers of Japanese soldiers were still hiding in Guam’s jungles. The Third and Ninth Marines defeated many of the remaining soldiers over the following days.

On August 10, 1944, patrols from the 77th Infantry Division approached Obata’s command post at Mt. Mataguac. A full-scale battle ensued. Obata knew the end was near and radioed his last messages to Japan: "I will engage the enemy in the last battle with the remaining strength at Mount Mataguac tomorrow, the 11th." The next morning, U.S. soldiers assaulted the hill, then descended into the depression where they sealed the caves with several 400-pound blocks of TNT. The explosion killed the remaining defenders, including Obata.

1,769 Americans died during the Battle of Guam. 23,303 Japanese defenders died between July and September on Guam. Less than 1,500 surrendered. Admiral Nimitz established his forward CinCPac-CinCPOA headquarters in Guam and directed the rest of the war in the Pacific from the island.

War in the Pacific National Historical Park burgeons with life. Scars and stains of World War II still remain on many Pacific islands, but over time, vibrant plant and animal communities have dramatically rebounded. Within the park's boundaries lie coral reefs, seagrass beds, tropical savanna grasslands, limestone forests, bogs, streams, coastal and forest wetlands, offshore islets, and even a mahogany forest!

These outstanding environments create homes for rare animals and provide a laboratory for scientific inquiry and research. Become acquainted with Guam's outdoor wonders - and learn more about the NPS Inventory and Monitoring Program that keeps tabs on many of the plants, animals, and weather throughout Pacific island national parks.

The changing environment is threatening the health of Guam's coral reefs. Discover the problems coral reefs face.

In response to stresses such as higher water temperatures, corals can lose the symbiotic microscopic algae, causing them to look bleached.

Follow researchers as they monitor clams and coral bleaching, and learn more about summer programs at the park.

Coconut, breadfruit, pandanus, limeberry, indian mulberry, and half flowers were transported to the Mariana Islands by a seafaring people, now known as the CHamoru. These ancient voyagers arrived on Guam approximately 4,000 years ago. The six culturally significant plants along the trail at Asan Ridge are deeply entwined in the history and culture of the CHamoru people.

The Coconut Palm, called the “Tree of Life”, is traditionally used for food, drink, oil, building material, and animal feed.

Breadfruit, brought to Guam by the prehistoric navigators who first settled the island, is an important food source for humans.

The main use of the Pandanus tree was through its leaves, which were traditionally used as a material for weaving.

The Limeberry was an important food for the Marianas Dove, a native bird which is now extinct on Guam.

Indian Mulberry is not typically used as food due to its unpleasant smell. Instead the roots, leaves, and bark have been used medicinally.

Asan Beach is one of seven units that make up War in the Pacific National Historical Park War in the Pacific National Historical Park While Guam is only 212 square miles, the island is rich in history. The island was captured by Imperial Japanese forces just days after the attack on Pearl Harbor, and remained under Japanese control for 31 months until July 21, 1944 when the United States returned and liberated the island . Many lives were lost, and the suffering was great for all those involved in the battles on Guam and throughout the Pacific theater. In order to remember the United State's and Guam's involvement in World War II, War in the Pacific National Historical Park was established in 1978 to commemorate the bravery and sacrifice of those who participated in the campaigns of the Pacific Theater of World War II and to conserve and interpret outstanding natural, scenic, and historic values and objects of the island of Guam. The park is made up of six developed units, plus the undeveloped Mt. Alifan Unit. Each one tells a different story from the war.

Start your visit with a 10-minute video about the Battle for Guam at the visitor center, home to a museum, bookstore and historic submarine.

Explore remains of fortifications used by Imperial Japanese troops during the Battle of Guam at the Agat Unit.

Remember those who lost their lives or suffered atrocities on Guam during World War II at the Asan Bay Overlook.

Walk in the footsteps of the Third Marine Division at the Asan Beach Unit, one of two landing sites used on July 21, 1944.

See the remains of the Imperial Japanese communications center at the Fonte Plateau Unit.

Hike through the jungle to three Imperial Japanese coastal defense guns at the Piti Guns Unit.