Marines in World War II Commemorative Series
Base Defense in a Possible War with Japan
An Organization for Base Defense
Organization and Equipment for the Defense Battalion
The Approach of War
The Saga of Wake Island
A Defensive Buildup
Two African-American Defense Battalions
The South Pacific
South Pacific Tales
Into the Central and Northern Solomons
Fighting Boredom
The Central Pacific Drive
Signs of the Times
Reorienting the Defense Battalion
Tributes to the Defense Battalions
Pacific Victory
Gone But Not Forgotten
Battalion Summaries
Special Subjects
Shoulder Insignia
Antiaircraft Artillery
Antiaircraft Machine Guns
Coast and Field Artillery
Fire Control
Armor and Support

CONDITION RED: Marine Defense Battalions in World War II
by Major Charles D. Melson

Reorienting the Defense Battalion

At Marine Corps headquarters, General Vandegrift, now the Commandant, faced a problem of using scarce manpower to the greatest possible effect. Vandegrift's director of the Division of Plans and Policies, Gerald C. Thomas, promoted to brigadier general, received instructions to maintain six divisions and four aircraft wings, plus corps troops and a service establishment — all without a substantial increase in aggregate strength. Most of the men that Thomas needed already were undergoing training, but he also recommended eliminating special units, including the defense battalions. Abolishing the defense battalions promised to be difficult, however, for the Navy Department felt it would need as many as 29 battalions to protect advance bases. General Vandegrift exercised his powers of persuasion on Admiral Ernest J. King, the Chief of Naval Operations, and talked the naval officer into agreeing not only to form no new defense battalions but also to accept deactivation of two of the existing 19 units, while reorienting the 17 survivors to meet the current threat. The process began in April 1944, and five months later, the defense battalions that began the year had converted to antiaircraft artillery units, though a few retained their old designation, and in rare instances the 155mm artillery group remained with a battalion as an attachment rather than an integral component.

A new table of organization appeared in July 1944 and reflected the emphasis on 90mm and 40mm antiaircraft weapons, though it left the manpower level all but unchanged. The document called for a battalion of 57 officers and 1,198 enlisted men, organized into a headquarters and service battery, a heavy antiaircraft group, a light antiaircraft group, and a searchlight battery. Only three units retained the designation of defense battalion until they disbanded — the 6th, the 51st, and the 52d. In the end, most of the defense battalions became antiaircraft artillery outfits and functioned under the Fleet Marine Force, Pacific.

Coast and Field Artillery

The first defense battalions were equipped with 5-inch/51-caliber naval guns which were originally designed for shipboard mounting and later extensively modified for use ashore. These weapons were then emplaced in static positions, but with great difficulty. The guns fired high explosive, armor piercing, and chemical shells.

Initially, the defense battalions were issued the standard M1918 155mm "GPF" guns, which had split trails, single axles, and twin wheels. These World War I relics deployed to the South Pacific with the defense battalions. Later, the battalions were issued standard M1A1 155mm ""Long Tom" guns. This piece weighed 30,600 pounds, had a split trail and eight pneumatic tires, was pulled by tractor, and was served by a combined crew of 15 men. It was pedestal mounted on the so-called "Panama" mount for its seacoast defense role. It combined great firepower with high mobility and proved to be a workhorse that remained in the inventory after World War II.

While these changes were taking place, defense battalions participated in the final phase of the Central Pacific campaign — three successive landings in the Mariana Islands by V Amphibious Corps and III Amphibious Corps, and the destruction by American carrier pilots of the naval air arm that Japan had reconstituted in the two years since the Battle of Midway. In the Marianas, the Marines stormed large islands, with broken terrain overgrown by jungle, a battlefield far different from the compact, low-lying coral outcroppings of the Gilberts and Marshalls. The Marianas group also differed from the recently captured atolls in that the larger islands had a sizable civilian populace that had lived in towns flattened by bombs and artillery.

On 15 June 1944, the conquest of the Marianas began when V Amphibious Corps attacked Saipan with the 2d and 4th Marine Divisions, backed by the Army's 27th Infantry Division. The 17th Defense Battalion, under Lieutenant Colonel Thomas G. McFarland, reached Saipan in July, where the 18th Defense Battalion, led by Lieutenant Colonel William J. Van Ryzin, joined it and became part of the island garrison. Although Saipan was by now officially secure, danger from various tropical maladies persisted. After a briefing on the island's innumerable health hazards, Technical Sergeant John B. T. Campbell heard a private ask the medical officer "Sir, why don't we just let the Japs keep the island?"

On 24 July, Marines boarded landing craft on Saipan and sailed directly to Tinian, the second objective in the Mariana Islands. McFarland's battalion landed at Tinian in August and devoted its energy to building and improving gun positions, roads, and living areas. The battalion's historian, Charles L. Henry, Jr., recalled that "round-the-clock patrols were still a necessity, with many Japanese still on the island." Skirmishes erupted almost daily, as Marines from the battalion "cleaned up the island." The 18th Defense Battalion moved from Saipan to Tinian, where the 16th Defense Battalion joined it in September to help protect the new airfields.

10th Defense Battalion test firing a 155mm gun
On drab, desolate Eniwetok, the 10th Defense Battalion test fires a 155mm gun out across an empty ocean. Despite the lack of threat of any immediate enemy attack, the weapon was camouflaged just in case Japanese planes flew over. Department of Defense photo (USN)

On 21 July 1944, the 9th Defense Battalion, commanded by Lieutenant Colonel Archie E. O'Neil, and the 14th, under Lieutenant Colonel William F. Parks, landed on Guam. The two units served with distinction in the recapture of the island by the 3d Marine Division, 1st Provisional Marine Brigade, and the Army's 77th Infantry Division under the overall control of III Amphibious Corps. The 9th Defense Battalion supported the Marine brigade at Agat Bay, and the 14th protected the 3d Marine Division on the Red Beaches, where it landed under intense fire, prepared the beachhead defenses, set up antiaircraft guns, and later helped rescue civilians made homeless by the war. An account prepared by the 3d Marine Division related that, although Guam was secured rapidly, "the fighting was not over" by August, for more than 10,000 disorganized Japanese stragglers held out in the northern part of the island until they fell victim to "the long, grueling process of mopping up." Both defense battalions also bore the twin burdens or working as laborers and doubling as infantry in searching out the Japanese and killing or capturing them.

barrage from the 12th Defense Battalion
A violent barrage from the 12th Defense Battalion greets attacking Japanese aircraft over Cape Gloucester, New Britain. As the danger from Japanese surface ships diminished, the defense battalions became concerned with Japanese air raids. Photo courtesy of the U.S. Naval Institute

The captured Mariana Islands demonstrated their strategic value in November 1944, when Boeing B-29s based there began the systematic bombing of targets in Japan's Home Islands. From the outset, Marine antiaircraft gunners helped defend these airfields. Eventually, the African-American 52d Defense Battalion, commanded by Lieutenant Colonel David W. Silvey, reached the Marianas after service at Roi-Namur and Eniwetok, where it had replaced the 1st and 15th battalions. The 52d set up its antiaircraft weapons on Guam in the spring of 1945, patrolling for Japanese stragglers and providing working parties. The emphasis on labor caused one noncommissioned officer to observe that instead of "being a defense unit, we turned out to be nothing more than a working battalion," a complaint that members of other defense battalions would echo.

Despite constant patrolling and frequent clashes with the die-hard Japanese, duty in the Marianas became a matter of routine. The same pattern prevailed throughout the captured Gilberts and Marshalls, as well. Aviation units manned the airfields; antiaircraft gunners peered into an empty sky, hoping the enemy would appear; those members of defense battalions not otherwise employed wrestled cargo between ship's holds and dumps ashore; and Seabees sweated over construction projects.

fire from Marine antiaircraft gunners
The fire from Marine antiaircraft gunners defending the Saipan beachhead against a Japanese night air attack makes interesting "4th of July" patterns in the sky. Department of Defense photo (USCG)

Marines of Battery I, 14th Defense Battalion
Marines of Battery I, 14th Defense Battalion, man their twin-barrelled, Mark IV, Oerlikon-designed 20mm guns on top of Chonito Ridge overlooking Adelup Point. In the initial stages of the Guam operation, these antiaircraft guns were in support. Department of Defense photo (USMC) 93063

While the Central Pacific campaign moved through the Gilberts, Marshalls, and Marianas, the 1st Marine Division, after wresting control of New Britain and isolating Rabaul, prepared to seize Peleliu in the Palau Islands to protect MacArthur's flank as he reentered the Philippines. The division landed on 15 September 1944, triggering a bloody battle that tied down the bulk of the division until mid-October. Army troops did not crush the last organized Japanese resistance until the end of November. During the bitter fighting on Peleliu, the 12th Defense Battalion, now redesignated an antiaircraft artillery unit, supported the Marine division while it fought to conquer the island. Also present on Peleliu — described as "the most heavily fortified ground, square yard by square yard, Marines have ever assaulted" — was the light antiaircraft group of the 4th Antiaircraft Artillery (formerly Defense) Battalion. The 7th Defense Battalion, now an antiaircraft outfit, worked with the Army's 81st Infantry Division on Anguar, remaining there after the soldiers took over the fighting on Peleliu.

The Marine antiaircraft gunners at Peleliu dug in on what was described as "an abrupt spine of jagged ridges and cliffs — jutting dragon-tooth crags, bare and black, where Marine infantrymen fought maniacal Japs." As the fury of the fighting abated, the 7th Battalion transferred personnel and equipment to the 12th, which — according to its logistics officer, Harry M. Parke — received newer material and "men with less time overseas," who would not become eligible to return home when the units began preparing for the invasion of Japan.

By the end of 1944, with Peleliu and the Marianas firmly in American hands, 74,474 Marines and sailors served in island garrisons and base defense forces. As the defense battalion program focused on antiaircraft weapons, defense units — most of them by now redesignated as antiaircraft artillery outfits — served in Hawaii (the 13th at Oahu with the Fleet Marine Force, Pacific; the 8th on Kauai with Fleet Marine Force, Pacific; and the 2d, 5th, 7th, and 16th with V Amphibious Corps) and at Midway (the 6th). In the Southwest Pacific, battalions were stationed at Guadalcanal (the 3d and 4th with III Amphibious Corps), the Russell Islands (the 12th with III Amphibious Corps), and the Ellice Group (the 51st). Locations in the Central Pacific included Eniwetok (the 10th with V Amphibious Corps), Guam (the 9th and 14th with III Amphibious Corps), Majuro (the 1st with V Amphibious Corps), Roi Namur (the 15th with V Amphibious Corps), and Saipan (the 17th and 18th with V Amphibious Corps). The 52d Defense Battalion, which would reach Guam in the spring of 1945, stood guard at Majuro and Kwajalein Atolls.

optical gun director
An optical gun director is manned by Marines from one of the defense battalions participating in the Peleliu operation. Fortunately for the attacking 1st Division Marines, no enemy air appeared overhead to hazard the ground operations. Department of Defense photo (USMC) 97571

SCR-584 radar
This Army-developed SCR-584 radar took over the work of the optical gun director on Peleliu, to provide automatic target tracking and gun laying for the Marines. Department of Defense photo (USMC) 97570

Fire Control

A combination of conventional optical sights coincidence range finders, sound locaters, primitive radar sets, and searchlights comprised the fire control equipment in the early defense battalions. As the war progressed in the Pacific, most of these items were modified and improved.

The Sperry 60-inch searchlight fired up a 800-million-candlepower light beam with a slant range of 20,000 yards. Originally intended for illuminating ships at sea, the Sperry was soon employed in finding and tracking enemy aircraft overhead. The searchlights were also used to direct night fighters to intercept enemy planes, to guide friendly aircraft back to their bases, and in support of ground forces as their beams were reflected off of low cloud cover in order to illuminate the battlefield.

Searchlights, radar, and sound detectors worked in conjunction with gun directors to convert tracking information into firing data. Gun directors functioned as computers in providing the trigonometic solutions which predicted flight paths and furnishing fuze settings for the antiaircraft artillery. The input of height finders combined with information about the azimuth and elevation of the targets also was fed to remotely controlled 40mm and 90mm antiaircraft guns.

The radar and fire control equipment employed by the defense battalions in turn allowed them to become an integral part of the overall air defense of a captured target area. Although dispersed throughout the beachhead, this equipment was linked primarily by telephone with a radio backup. A battalion fire control center coordinated the operations of each group of weapons and in turn was incorporated with other Allied radar nets. The effective ranges for fire control equipment was variously 20-45 miles for fire control gear and 120-200 miles for search radar.

Tributes to the Defense Battalions

Master Technical Sergeant Alvin M. Josephy, Jr., a Marine combat correspondent, wrote in 1944 that "since the beginning of the war many of the men . . . had seen action in units smaller than divisions — in defense and raider battalions and other special commands." These Marines "had been fighting for a long time," he said. Leatherneck, a magazine published by and for Marines, predicted in September 1944 that not until the war was won would the complete story of each defense battalion be told. Because of the vital part they played, "much information about them . . . must be withheld, but there are no American troops with longer combat records in this war."

Next Page Document Cover Next Page
MARINES The Few. The Proud.
Back to Top
Commemorative Series produced by the Marine Corps History and Museums Division