Marianas 1944:
The Invasion of Guam, 1941
By Mike Bennighof, Ph.D.
October 2022

American possession of Guam, a Spanish colony since 1668, came about almost accidentally. In June 1898 the cruiser Charleston, convoying troop transports to Manila in the Philippines, stopped off to lob a few shells at the island. Unaware of the Spanish-American War, the island’s governor had himself rowed out to the cruiser to apologize for not returning what he believed to be a salute, for his small coast-defense battery had no ammunition.

Informed of the new war, the governor promptly surrendered. After the war’s end, the United States kept the island for use as a coaling station and later a telegraph post connecting the U.S. West Coast and the Philippines. Spain had used the island for the same purpose, as a way station for the Manila Galleon sailing to and from Acapulco, and once those voyages ended Guam had become even more of a backwater.

Under American rule, Guam remained a backwater. Alfred Thayer Mahan, the influential naval theorist of the early 20th Century, pressed for it to become the “Gibraltar of the Pacific.” Instead it housed a small garrison of Marines and sailors, with a naval officer serving as military governor.

The Marines built a barracks near the capital, Agana, in 1901 and the Navy installed a coast-defense battery of six-inch guns in 1909. The Washington naval limitations agreement of 1922 forbade the fortification of the Pacific Islands, and the coastal guns were removed from Guam in 1930. The Navy’s Hepburn Board charged with reviewing American military preparedness proposed fortifying Guam in 1938, but Congress refused funding even though the Washington treaties had lapsed. Pan American Airlines built a seaplane facility outside Agana in early 1935, and by the end of the year Guam was a regular stop for the Manila Clipper, the first regular trans-Pacific airline service. But Guam had no conventional airfield.

By 1941, Guam had a population of just over 23,000, almost all of them of the indigenous Chamorro people. It exported small quantities of copra (dried coconut meat), rice, sugar and corn. Economically inconsequential, it had no representation in Washington and the islanders had no recourse against the naval governor’s directives.

Japanese troops land on Guam. Painting by Kohei Izaki.

The Marine garrison numbered 153 men, commanded by Lt. Col. William K. MacNulty. Of those, 28 had been seconded to the Guamanian police force, known as the Insular Patrol. Guam had its own forces as well, known as the Insular Force Guard, which numbered 80 regulars and 243 poorly-trained and -armed militia. The regular Guard was armed and paid by the Navy (at half the rate of corresponding white ratings); the militia were unpaid and armed with a collection of aged rifles and pistols scavenged over the preceding decades from passing Navy ships.

Naval forces consisted of the Lapwing-class minesweeper Penguin, a 1,000-ton craft armed with two 3-inch guns and carrying a crew of 78. Another 271 regular Navy personnel manned the radio station, government offices and other functions. The most recent U.S. Navy war plan for the Pacific, known as Rainbow 5, simply assumed that the Japanese would occupy Guam in the war’s first days without much trouble.

With war approaching, the Navy evacuated all dependents in October 1941. Following telegraphed warnings, the island’s governor, Navy Capt. George McMillin, ordered his staff to burn all of its classified papers on 6 December 1941.

McMillin received word of the attack on Pearl Harbor at 0545 on 8 December (almost immediately after it began), and three hours later Japanese bombers based on Saipan appeared overhead, concentrating their attacks on the Penguin. Penguin returned fire as best she could, shooting down one bomber, but numerous near-misses shattered her hull and she quickly took on water. Her skipper, Lt. James W. Haviland, coaxed his battered ship into deeper water where the crew scuttled her; over 60 of the 78 men had been wounded by the bombs and repeated strafing, and one killed.

The valiant Penguin, victim of Japanese aggression.

Following their destruction of the valiant Penguin, the bombers next worked over the oil storage tanks at Apra Harbor, the radio station and the Marine barracks. Japanese planes also strafed native villages and attacked people along the roads outside Agana. McMillin ordered all civilians out of the capital, and arrested all Japanese who could be found.

That night, three Saipan natives showed up in a canoe, bearing warning that the Japanese planned to land the next day. The landings actually began a day later on Dunggas Beach north of Agana, exactly where the Saipanese – apparently Chamorro interpreters unwillingly pressed into Japanese service – had predicted.

The Marines had dug themselves in on their rifle range, which also commanded the approaches to Apra Harbor. The Insular Guard took up positions in government buildings within Agana. Japanese naval infantry from the 2nd Maizuru Special Naval Landing Force troops hit the beaches first, followed by Army troops from the South Seas Detachment (formed from the 55th Infantry Division to occupy Rabaul after Guam had been secured). Nine transports brought them from Saipan, with close escort provided by the minelayer Tsugaru and four destroyers, and distant cover by the heavy cruisers Kako, Aoba, Furutaka and Kinugasa.

Fighting broke out between the SNLF troops and the Insular Guard around Agana’s main plaza; the Marines held themselves ready on the rifle range and did not intervene. McMillin ordered the Insular Guard to stand down and surrender, and sent word to the Marines to do so as well. That apparently did not reach MacNulty until skirmishing had already erupted between the Marines and some Imperial Army troops. All fighting had come to a close by the end of the day.

American propaganda would later claim that more determined resistance occurred, but this is not true. A handful of the Marines attached to the Insular Patrol refused to surrender, but by late 1942 the Japanese occupation forces had tracked down and executed all but one of them. Casualty figures vary wildly depending on the source, but it appears that the Marines suffered four dead and 12 wounded during the one day of fighting, and the Insular Guard 15 killed and 30 wounded. The U.S. Navy lost eight men killed during the fighting and five radiomen beheaded afterwards; thirteen civilians were also killed. Japanese losses totaled one killed and six wounded.

The Japanese settled in for what they intended as a permanent occupation. Schools were eventually re-opened and taught the Japanese language and reverence for the Emperor, while English was forbidden. In early 1944 things changed as the American counter-offensive approached the Marianas, with schools closed and all the islanders forced to labor on Japanese fortifications and airfields. Food was scare, and summary executions common. Afterwards the Japanese forced them into concentration camps, which would spare those who survived the Japanese from American bombs and shells during the liberation of Guam in July 1944.

Our Panzer Grenadier: Marianas 1944 book includes a Guam 1941 scenario, but it represents more of a take on what could have happened rather than what actually did – the Marines and Insular Guard did not fight together, most of the Guard was poorly armed, and neither Marines or Guards opposed the Japanese landings. Since the scale of the actual fighting barely rates representation at the Panzer Grenadier scale, that’s about the only way the designer had to get the Guamanians into action.

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Mike Bennighof is president of Avalanche Press and holds a doctorate in history from Emory University. A Fulbright Scholar and NASA Journalist in Space finalist, he has published a great many books, games and articles on historical subjects; people are saying that some of them are actually good. He lives in Birmingham, Alabama with his wife, three children, and new puppy. He misses his lizard-hunting Iron Dog, Leopold.

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