Original Item: Only One Available. Totally inert and demilitarized according to BATF guidelines with hollow body and no charge. This AN-M57 General Purpose bomb cannot be converted to an explosive device.

Not Available For Export

Prior to World War II, the military determined that the Modified Mark series of bombs were obsolete, requiring newer and up-to-date bombs to be developed. Both the U.S. Army and Navy began development of their own series of bombs, the Army with the "M" series and the Navy with their "Mk" series. Both similar, these bombs were designed with parallel sides, an ogival nose and a boat tail which is a box type-tail reinforced to prevent warping and aid with accurate drops. Due to the shortage of T.N.T., the Army filled their bombs with 50/50 Amatol with T.N.T. ends to seal in the Amatol and protect it from moisture. The Navy, on the other hand, continued to manufacture their bombs with 100% T.N.T.

With the approach of World War II, the U.S. Army (including the Army Air Corps) and the Navy standardised their series of bombs allowing for interchanging between services, consolidating manufacturing capabilities and allowing for modifications which enabled British service aircraft to mount these bombs too. Even after the standardisation of bombs in 1941, the standardisation process went through a few phases of further refinement, the first of which changed all high-explosive bombs to be termed general purpose (G.P.) or general purpose high-explosive (G.P.H.E). Later the designation of "demolition bomb" would come back for a few specific bombs.

When bombs are dropped, there is always a chance that something in the explosive train of the bomb will fail and it will not explode. Early AN style bombs were defusable in the event that they did not explode on contact, meaning that any unexploded AN bomb could have the fuses and boosters removed without the bomb exploding, rendering it inert. To counter this and allow for the potential "dud" bomb to explode when tampered with, the AN G.P.H.E. series bombs with the modification "A1" annotated that these bombs now had special pins mounted in the bomb's baseplate which fused with the explosive filler making it impossible to remove the booster without causing the bomb to detonate. Other modifications later added would include minor changes to the bomb body or the type of explosive filling used. During this time a second option for bomb tails was added, the box-type tail was already the mainstay of the bombs, however, to create a more aerodynamic bomb a conical tail assembly was added. This stretched out low profile tail improved the aerodynamics of the carrying aircraft, allowing it to carry more ordnance.

This general purpose bomb was rendered inert and obviously was not utilized during the war. This bomb was painted to be a display piece at an enlisted man’s club for the 18th Coastal Defense Battalion, 2nd Marine Division. Most of the original paint has been retained but some of the yellow paint appears to have been touched up. The tail fins each have writing on them but the unit identifier is written as followed:

18TH DEFENSE
BN.
F.M.F.
2 DIV
U.S.M.C.

The bomb stands at approximately 41” tall with a base of 8” squared. The other side of the base is marked "Merry Christmas 1942". This impressive piece comes more than ready to display!

Marine Defense Battalions
Marine Defense Battalions were United States Marine Corps battalions charged with coastal and air defense of advanced naval bases during World War II. They maintained large anti-ship guns, anti-aircraft guns, searchlights, and small arms to repel landing forces.

2d Antiaircraft Artillery Battalion (Composite)
The 2d Antiaircraft Artillery Battalion (Composite) (2d AAA Bn [Composite]) was a United States Marine Corps anti aircraft unit that served during World War II. Formed in 1943 as the 3d Airdrome Battalion, its original mission was strictly providing air defense. On 1 October 1943 the battalion was redesignated the 18th Defense Battalion. During the war the battalion provided air defense for the Saipan and Tinian area of operations. The battalion returned to Marine Corps Base Camp Lejeune, North Carolina after the war receiving its final designation on 16 May 1946. The battalion was decommissioned in September 1947.

History
The 3d Airdrome Battalion was commissioned on 15 July 1943 at Marine Corps Base Camp Lejeune, North Carolina. The Airdrome battalions were essentially defense battalions minus the coastal defense capabilities. The Marine Corps had planned to utilize them to defend airfields overseas. On 1 October 1943 the battalion was re-designated as the 18th Defense Battalion. 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. Because of the divestiture of the coastal defense mission, the battalion was re-designated as the 18th Antiaircraft Artillery Battalion on 15 May 1944.

The battalion departed from San Diego, California in late June 1944 and arrived at Pearl Harbor, Hawaii in early July 1944. By August 1944 elements of the battalion were located on both Saipan and Tinian. The battalions was finally consolidated on Tinian by September 1944. It remained on Tinian providing air defense coverage for the remainder of the war. In January 1946 the battalion embarked onto the USS Manila Bay and USS Wheatland (AKA-85) to return to the United States. It arrived at Marine Corps Base Camp Lejeune in February 1946.

By May 1946, the 9th and 18th Antiaircraft Artillery Battalions were the last two remaining. They were re-designated as the 1st and 2d Antiaircraft Artillery Battalions (Composite).