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 as activated at Marine Barracks, Parris Island, South Carolina on 1 February 1942.[2] Originally a training detachment, it consisted of 75 enlisted men sent over from the 5th Artillery Group located at Parris Island.[3] The 13 February 1942 the battalion departed from Naval Station Norfolk, Virginia onboard the USS William P. Biddle (APA-8) arriving at Guantanamo Bay, Cuba on 19 February.[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.

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.[5] The battalion setup its weapons at Koli Point, and promptly shot down a dozen enemy planes.[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] Elements were progressively moved onto the island of New Georgia to support the Drive on Munda Point 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.[8] They were tasked with air defense and coastal and perimeter defense of the area from Agat south to Bangi Point.[9] 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.[10]

The battalion was redesignated on 12 May 1946 as the 1st Antiaircraft Artillery Battalion. On 30 November 1949 the battalion was again redesignated, this time to the 1st 90mm Antiaircraft Artillery Gun Battalion. The last redeisgnation came less than a year later on 21 August 1950 when it was titled the 2nd 90mm Antiaircraft Artillery Gun Battalion. The unit was transferred to Marine Corps Base 29 Palms, CA in October 1953. The battalion was deactivated on 15 September 1956.[1]