USMC 8th Defense Battalion, Fifth Amphibious Corps, info request

Hey all! looking for any info anyone can give on the above unit. My grandfather was with them for a bit, he was a Field Artillery and Heavy Artillery crewman, mostly on 155mm Howitzer M114s; i have his full military record and additional records from NPRC pertaining to the *entirety* of his 3 year service ... except this one little 3 month period with the 8th Defense Battalion. Heres what i know:

Arrived at Apamama in the Gilberts Nov 28 1943. Arrived via the USAT Jane Adams. Attacked by Air, on Apamama January 2nd, 3rd, and 10th 1944.
I have a 'Battalion Promotion Order' dated Feb 11 1944, Apamama Gilbert Islands, which has the designation 'Eighth Defense Battalion' on top, so i'm assuming they were still at Apamama at that time. This Promotion order is broken up into three sections: HQ and Service Battery: Seacoast Artillery: Antiaircraft Artillery.

...But thats all i have.
From several personnel rolls, i have deduced that my grandfather and a BUNCH of other guys were either transferred or redesignated to the 12th 155mm Artillery Battalion (on April 16 1944) and then later to the 5th 155mm Artillery Battalion (with which my Grandfather was one of only 1200 Marines to help MacCarthur retake the Philippines in Oct 1944 on Leyte).

Any info or pointers regarding the 8th Def Battalion, what they were doing on Apamama, anything at all, would be most appreciated thank you all

 

There are a couple of lines on Hyperwar;

HyprWar: "Condition Red: Marine Defense Battalions in World War II"

"8th Defense Battalion
(April 1942-April 1944)
Lieutenant Colonel Augustus W. Cockrell raised this battalion from Marine units at Tutuila, Samoa. In May 1942, the battalion deployed to the Wallis Islands, where it was redesignated the Island Defense Force. Lieutenant Colonel Earl A. Sneeringer assumed command for two weeks in August 1943 before turning the unit over to Colonel Clyde H. Hartsel. Colonel Lloyd L. Leech became battalion commander in October 1943, a month before the unit deployed to Apamama in the Gilberts. On 16 April 1944, after moving to Hawaii, the organization became the 8th Antiaircraft Artillery Battalion and, as such, took part in the Okinawa campaign, remaining on the island until November 1945 when the unit returned to the United States."

The Defense Battalions were generally organised as a HQ & Service Battery, an Anti-aircraft Artillery Group, a Special Weapons Group and a Seacoast Artillery Group. Around April 1944 the Seacoast guns were removed and the Defense Battalions became Anti-aircraft Artillery Battalions. Also at this time the USMC began raising new, non-Div artillery units, including 155-mm Gun Battalions. These were largely derived from the now defunct Seacoast Artillery Groups, which were primarily armed with 155-mm guns, though 5-in and 7-in guns could be used.

The "US Marine Corps World War II Order of Battle" (Rottman) notes that the 8th Defense Battalion contributed to the raising of the 8th 155-mm Gun Battalion. It also lists two incarnations for the 12th 155-mm Gun Battalion, the first being formed in April 1944, then a few moths later being converted to a 155-mm Howitzer Battalion, and being re-designated the 5th 155-mm Howitzer Battalion in July 1944. A new 12th 155-mm Gun Battalion was raised shortly after.

Gary