2nd 90mm Antiaircraft Artillery Gun Battalion

US Marines from the 9th Defense Battalion on New Georgia or Rendova manning a 90mm AA gun around July or August 1943.

The 9th Defense Battalion was commissioned at Marine Barracks, Parris Island, South Carolina on February 1, 1942.[2] Originally a training detachment, it consisted of 75 enlisted men sent over from the 5th Artillery Group located at Parris Island.[3] On February 13, 1942 the battalion departed from Naval Station Norfolk, Virginia onboard the USS William P. Biddle (APA-8), sailed through axis submarine infested waters, arriving at Guantanamo Bay, Cuba on February 19.[3] The battalion consisted of 3 batteries 90mm AA artillery; 2 batteries 155 mm “Long Tom” seacoast artillery; 3 batteries each 40mm, 20mm and 50 caliber weapons designed as both anti-tank and anti-air artillery. Together with fire control apparatus, transport, and support units the battalion comprised about 1,300 men.

At Guantanamo Bay the battalion was charged with two missions. The first was to quickly develop into a fully operational defense battalion and the other was to assist in the defense of the Naval Base. While in Cuba the battalion trained extensively in both infantry tactics and its air and coastal defense missions. On October 4, 1942 battalion personnel and equipment were loaded onto the USS Kenmore (AP-62), SS Robin Wentley, and USS Fairisle headed for an unknown destination.

After Guantanamo Bay the battalion was sent through the Panama Canal to Noumea, New Caledonia where equipment was trans-loaded onto the attack transport USS Hunter Liggett that took the battalion to Guadalcanal in November 1942.[4] The battalion setup its weapons at Koli Point, and promptly shot down a dozen enemy planes.[5] By May 1943, malaria had taken a heavy toll on the battalion thus requiring a significant influx of replacements.[6]

In June 1943 the battalion left Guadalcanal and took part in the Landings on Rendova, set up its artillery and fought off attempts by the Japanese to regain control. The battalion's 155 mm “long Tom” artillery shelled Japanese positions on New Georgia across the Blanche Channel and the unit's 90 mm batteries and Special Weapons Group shot down 24 Japanese aircraft during July.[7] At noon on July 2, the battalion's SCR-602 and SCR-270 radars were inoperable when a large Japanese formation of aircraft attacked the Rendova beachhead. This attack killed more than 30 Americans, wounded another 200+ and caused extensive damage to infrastructure, fuel dumps and the battalion's 155 mm artillery.[8]15% of the 155mm artillery battery was killed or wounded in the raid.[9] On the 4th of July, another large Japanese air raid was sent against the Rendova beachhead. A flight of 16 Betty Bombers and their escorts made it through the allied combat air patrol. Before the bombers expended their ordnance, they were engaged by the 90mm guns of Captain Bill Tracy's "E" Battery. Battery E succeeded in downing 12 of the bombers and one fighter while expending only 88 rounds of ammunition.[10][11]

Elements were progressively moved onto the island of New Georgia to support the Drive on Munda Point, defend against Japanese forces that broke into the rear lines, and later defend the Munda Airfield and assist in the operations to seize the surrounding islands (e.g. during the Battle of Arundel Island).

The 9th Defense Battalion deployed light antiaircraft guns, such as this Bofors 40mm weapon, in the Solomons on Rendova and New Georgia, both to protect the Zanana beachhead and to support the accelerating advance against the Munda airfield.

After securing New Georgia the battalion was moved to Mbanika in the Russell Islands for a period of rest and relaxation prior to its next assignment that involved the recapture of Guam in the Marianas Islands.

The battalion landed near Agana, Guam on 21 July 1944.[12] They were tasked with air defense and coastal and perimeter defense of the area from Agat south to Bangi Point.[13] On Guam most of the Japanese defenders retreated to the cliffs at the northern end of the island where thousands committed suicide by jumping to their deaths. The Battalion suffered from very high rates of dengue fever during the Guam campaign and while this was not fatal it did incapacitate many Marines.

Like all other defense battalions, the unit was re-designated as the 9th Antiaircraft Artillery Battalion on 1 September 1944.[2] The unit remained on Guam for the duration of the war and returned to Marine Corps Base Camp Lejeune, North Carolina in February 1946.[14]

While still located in Apra Harbor, Guam the battalion was re-designated on May 12, 1946 as the 1st Antiaircraft Artillery Battalion. In August 1948, the battalion embarked departed Guam onboard the USS George Clymer (APA-27) arriving at Courthouse Bay, Marine Corps Base Camp LeJeune, North Carolina on September 13, 1948. Upon establishing at Camp Geiger aboard MCB Camp LeJeune, the battalion continued to train in its primary mission of air defense. In October 1949, the battalion took part in Operation Normex, cold weather maneuvers that took place on the Labrador Peninsula, Canada.[15] On November 3, 1949 the battalion was again re-designated, this time as the 1st 90mm Antiaircraft Artillery Gun Battalion. The last re-designation came less than a year later on August 21, 1950 when the battalion was retitled as the 2nd 90mm Antiaircraft Artillery Gun Battalion. The last name change was required when the reserve 1st 90mm Antiaircraft Artillery Gun Battalion was activated for service during the Korean War. The 2d 90mm AAA Gun Bn continued training aboard Camp Geiger until October 1953 at which time the battalion embarked upon LSTs for transport to the west coast. The LSTs docked in San Diego and the battalion convoyed to its new base at Marine Corps Training Center Twentynine Palms, California.[15] The battalion was decommissioned on September 15, 1956.[1]