Guam Insular Guard
The Japanese forces who invaded Guam 10 December 1941 were fully prepared for the undertaking. Since mid-October, the Japanese 18th Air Unit, a small force of reconnaissance seaplanes, had conducted survey flights over and near Guam. By November, the unit was flying secret photo reconnaissance missions of the island at altitudes of 3,000 meters or higher.
The South Seas Detachment, a unit of about 5,500 army troops under the command of Major General Tomitaro Horii, and a special naval land force of about 400 men led by Commander Hiroshi Hayashi drawn from the 5th Defense Force stationed in Saipan, were assigned to capture Guam.
The Guam defending force was woefully undermanned: 274 US Navy personnel, more than half of them non-combative personnel; 153 US Marines; and about 120 Insular Force Guards, comprised of young CHamoru men recruited by the Navy eight months prior to the outbreak of WWII in the Pacific. The Guam defenders’ total arsenal were three machine guns, four Thompson submachine guns, six Browning automatic pistols, 50 .30 caliber pistols, a dozen .22 caliber regulation rifles, and 85 Springfield rifles. Most of the weapons were of World War I vintage. Imprinted on the Springfield rifles were labels with the following notation: Do not shoot. For training only.
Under cover of darkness in the early morning hours on 10 December 1941, a small group of Guam Insular Guardsmen took their battle position at the perimeter of the Plaza de España park. As the invading Japanese Imperial Army troops of overwhelming number came within range they opened fire and fought gallantly. After about half an hour of fighting, US Navy Captain George McMillan decided to surrender to prevent a senseless massacre of the Guam Defenders.
The defense at the Plaza de España was the only pitched ground battle fought against the invading enemy forces. They were armed with three machine guns and springfield single bolt action rifles and had limited military training. Pedro Cruz, one of the three platoon leaders who manned the machine guns, perhaps best expressed the sentiments of Guam’s defenders:
The only thought in my mind was: If I must die, I hope to God I kill some Japanese.Pedro Cruz
At 7 am 10 December 1941, Guam surrendered. Dead in the fighting at the Plaza and in small incidents around the island were 21 military personnel and civilians. The Japanese, though superior in force, also suffered casualties, but the number was never divulged. Dozens of men, particularly members of the Insular Force Guard, were interrogated and beaten during the first few weeks of occupation.
For further reading
Guam National Park Service. Guam Insular Guard: En Defende Y Tano-Ta, 1991. Memorial plaque. The Guam Insular Guard Monument, Hagåtña, GU.
Palomo, Tony, and Katherine Aguon. WWII: From Occupation to Liberation. In Guampedia, 2009.