10th Antiaircraft Artillery Battalion

The 7th Defense Battalion was commissioned on June 1, 1942 at Marine Corps Base San Diego, California.[3] Lieutenant Colonel Robert Blake was the battalion's first commanding officer.[4] At commissioning the battalion consisted of the following elements:

• H&S Battery
• 155mm Artillery Group
• 90mm AA Group
• Special Weapons Group

On August 21, 1942 the battalion embarked on the SS Day Star and sailed for the Territory of Hawaii. They arrived at Pearl Harbor on August 31, 1942 and proceeded to establish themselves at nearby Camp Catlin. Not long for Hawaii, the battalion departed on February 6 on board the USS Pinkney and the SS Robin Wentley. After a layover in Espiritu Santo they arrived at the Florida Islands on February 24, 1943. The first echelon of the battalion departed on March 14 for the Russell Islands. The remainder of the battalion arrived by March 28, 1943. "A" Battery was located on Pavuvu while "B" Battery was stationed on Mbanika. During May and June 1943, antiaircraft guns of the 10th Defense Battalion engaged numerous Japanese air raids against the newly constructed airfield on Banika. During this time the Commanding Officer of the 10th Defense Battalion also assumed the responsibilities as the Antiaircraft Commander, Russell Islands and Commander Marine Defense Group Solomons.

During July 1943, M3A1 Stuart Light Tanks of the 10th Defense Battalion were assigned to support the 43rd Infantry Division securing Munda Point on New Georgia.[5] After Munda, the tank section was transported via landing craft to Arundel Island where they again provided fire support for the 43rd Infantry during their seizure of the island.[6] On December 30, 1943 the US Army's 13th Antiaircraft Group assumed responsibility for air and coastal defense of the Russell Island.

From February 1-7 the battalion loaded on board the SS William H. Allen and the SS Sants Cruz. The ships departed the Russell Islands on February 10 and arrived at Tarawa where it received verbal orders to proceed to Kwajalein Atoll. Upon arrival off the coast of Kwajalein on February 18 the battalion received orders to organize a 500-man infantry unit (10th Defense Battalion Provisional Landing Force). It was going to serve as the V Amphibious Corps reserve for the upcoming assault on the atoll.[7] The 10th did not land on D-Day as Marines from the 22nd Marine Regiment accomplished the mission on February 22. The battalion went ashore on Eniwetok on February 24 and began set up air and coastal defense guns. It assumed responsibility for air defense of Eniwetok along with Air Warning Squadron 1 whose Air Defense Control Center provided early warning radar and Ground-controlled interception for fighters.

As the war progressed, the Marine Corps removed coastal artillery from the defense battalions in order to form additional heavy artillery units for the Fleet Marine Force.[8] Because of the divestiture of the coastal defense mission, the battalion was re-designated as the 10th Antiaircraft Artillery Battalion on May 31, 1944.[2] The seacoast artillery section departed Eniwetok on August 29 sailing for Kauai, Hawaii. Shortly thereafter on September 16 the 51st Defense Battalion assumed responsibility for defense of Eniwetok and Parry Islands.[9] The 10th Antiaircraft Artillery Battalion departed the Marshall Islands on September 17 and arrived in Kauai on September 27, 1944. The 10th Antiaircraft Artillery Battalion was decommissioned on November 25, 1944.[2]