The Approach of War

Beginning early in 1940, the defense battalions operated independently, or in concert with larger units, to secure strategic locations in the Atlantic and the Pacific. Colonel Harry K. Pickett's 3d Defense Battalion undertook to support the current War Plan Orange by occupying Midway Island on 29 September 1940, setting up its weapons on two bleak, sandy spits described by one Marine as being "inhabited by more than a million birds." Contingency plans for the Atlantic approaches to the Western Hemisphere called for deploying defense battalions in support of a possible landing in Martinique during October 1940, but the crisis passed. In February of the following year, the 4th Defense Battalion, under Colonel Jesse L. Perkins, secured the rocky and brush-covered hills overlooking Guantanamo Bay, Cuba. A composite unit of infantry and artillery, the 7th Defense Battalion, commanded by Lieutenant Colonel Lester A. Dessez, landed at American Samoa in March 1941 and became the first element of the Fleet Marine Force to deploy to the Southern Hemisphere during the prewar national emergency. Besides securing naval and air bases, the battalion trained a self-defense force of Samoan Marines.

Plans to forestall a German invasion of the Azores by sending a mixed force of soldiers and Marines, including defense battalions, proved unnecessary, but the most ambitious of the prewar deployments occurred in the Atlantic. In June 1941, Colonel Lloyd L. Leech's 5th Defense Battalion, less its seacoast artillery component, arrived in Iceland with the 1st Marine Brigade, which included the 6th Marines, an infantry regiment, and the 2d Battalion, 10th Marines, an artillery outfit. The brigade took over the defense of Iceland from British troops, releasing them from the protection of this critical region for even more important duty elsewhere. Once in place, the defense battalion and the other Marines assumed responsibility for helping keep open the Atlantic sea lanes to the United Kingdom.

On Iceland, 5th Defense Battalion Marines, attached to the 1st Provisional Marine Brigade, man a 75mm pack howitzer as British officers of the Iceland garrison look on. Note the polar bear patches on the right shoulders of the onlooking Marine officers. In the background are truck-mounted .50-caliber antiaircraft machine guns on special tripods. Photo courtesy of the U.S. Naval Institute

The 5th Defense Battalion set up its antiaircraft weapons, 3-inch guns and machine guns, around the Reykjavik airfield and harbor, where it be came the first Marine Corps unit to make operational use of the Army-developed SCR-268 and -270 radars. After-action reports covering the battalion's service in Iceland, declared that only "young, wide-awake, intelligent men" could operate the temperamental sets satisfactorily. Thanks to the efforts of the crews, the Marines proved able to incorporate their radar into the British air-defense and fighter-control system for "routine watches and training." Even though the battalion played a critical role in defending against long-range German patrol planes, its members also had to engage in labor and construction duty, as became common in other areas. Replaced by Army units, the last elements of the Marine garrison force left Iceland in March 1942.

Of the seven Marine defense battalions organized by late 1941, one stood guard in Iceland, five served in the Pacific — including the 4th, posted briefly at Guantanamo Bay — and another trained on the west coast for a westward deployment. The first Pacific-based defense battalions were nicknamed the "Rainbow Five" after the war plan in effect when the Japanese attacked Pearl Harbor. The five units were: the 7th in Samoa; the 6th, which took over from a detachment of the 3d at Midway Island; the 3d and 4th at Pearl Harbor, and the 1st divided among Pearl Harbor and Johnston, Palmyra, and Wake Islands. A sixth defense battalion, the 2d, remained in training in California.