United States Marine Corps Amphibious Reconnaissance Battalion - World War II-era

World War II-era

Three days after the attack of Pearl Harbor on December 7, 1941, the Japanese occupied the Gilbert Islands, and built a seaplane base on Makin that provided a token defense of Tarawa. They left a small number of Japanese Coastwatchers on Apamama, along with a few other atolls, to observe Allied forces in the South Pacific. It was after Carlson's Raiders that attacked Makin in August 1941 when the Japanese began to fortify and reinforce Tarawa, the largest and most strategically important atoll of the Gilberts. General Holland Smith mordantly blamed the Carlson raid for the rapid Japanese buildup and allegiantly felt, even after his retirement, that instead of subjecting heavy Marine casualties during the horrific and bloody seizure, Tarawa should have been avoided.

The joint amphibious force commander, Rear Admiral Richmond K. Turner, who was an effectual amphibious tactician, wrote a staunch dissertation over the mistakes during the Battle of Tarawa. Preeminent among the lessons scrutinized were that more and better aerial reconnaissance, more ships, landing crafts, amphibious tractors (or LVTs), and LCI Gunboats were needed. Three times the bombardment used at Tarawa in addition to increased pre-D-Day attacks by aircraft carriers, battleships, cruisers, and destroyers was extremely necessary. But above all, more use of submarine (periscope) reconnaissance was vital to pre-D-Day landings.

Aerial photography, submarine periscope photography and hydrographic reconnaissance by recon Marines and Navy UDT teams became part of the array of intelligence assets that were worked into the operation plan for the invasion. At the time, periscope photography was still new. Only a few ship captains had made single shots of sinkings, but Admiral Turner and General Smith were in need of more detailed and definitively located photographs of the beaches arranged in precise panoramic sequence. These would show enemy machine-gun and anti-boat gun emplacements as well as the locations of topographic features. Aerial photographs would be used in conjunction to provide a detailed photo interpretation.

Undoubtedly the most significant employment of reconnaissance in World War II occurred at Tinian. Far more important than the reputations which hung in the balance among the very top planners, were the thousands of lives undoubtedly saved as a direct result of reconnaissance efforts.

Pre-D-Day reconnaissance was limited because of Vice Admiral Turner. He was cautious about acknowledging Saipan as the main initial target. Also, he had also declined all pre-D-Day amphibious reconnaissance at Tarawa, which in hindsight, led to the controversial topic of whether his lack of prepared pre-D-day amphibious reconnaissance contributed to the high casualty rate of Marines.

The seizure of the Ogasawara archipelago and the Volcano Islands were outlined in the OCTAGON Conference in September 1944 between U.S. President Franklin D. Roosevelt, British Prime Minister Winston Churchill and the Combined Joint Chiefs of Staff. Due to General Douglas MacArthur's landing on Leyte, it made modifications to the Combined JCS initial directive for General MacArthur to further seize Luzon on the targeted date of December 1944 and Admiral Chester Nimitz to provide cover and naval support by seizing the Bonin Islands, or the lesser Volcano Islands, on or about January 20, 1945 and Okinawa in the Ryukyu Islands on or about March 1, 1945. Both the islands of Formosa and Amoy were to be bypassed due to their physical size, close proximity to Japanese air strikes and the large, substantial numbers of the Japanese Marines that were heavily fortified in the area.

Admiral Nimitz chose Iwo Jima instead of ChiChi Jima for seizure, the largest islet in the Volcano Islands. He acknowledged that it would provide airfields for the P-51 Mustangs, to escort the B-29 Bombers for bombing Tokyo on mainland Japan, traveling 625 nautical miles (1,200 km) north from the newly acquired airbases on the islands of Saipan and Tinian. The operation of Iwo Jima, codenamed DETACHMENT, was given to Admiral Spruance and RAdm Hill. by Admiral Nimitz. Iwo Jima was going to be the only major battle for 5th Marine Division, Task Force 56 (Expeditionary Troops) as a division-in-whole during World War II; however, half of the new 5th Division was formed by the enlisted Marines from prior engagements from other units.

Iwo Jima was the most heavily fortified island in the Japanese defenses, making it the bloodiest and costliest campaign in Marine Corps history. With news that the United States was delayed in the Iwo Jima operation, due to the support of Luzon and the campaigns in the Marianas, the Japanese took advantage of the opportunity in reinforcing their strength by attaching the 109th Infantry Division and adding heavier beach-defense weapons, artillery and tanks. Emperor Hirohito himself selected Lieutenant General Tadamichi Kuribayashi, a brilliant battle-hardened cavalry officer, as its commander.

The mission for Okinawa was given the codename ICEBERG. Operation ICEBERG was clarified when Admirals Ernest King and Chester Nimitz, Army's LtGen. Simon Buckner, commander of landing forces and LtGen. Millard "Miff" Harmom of the Army Air Corps met in San Francisco, CA, for finalization of the invasion plans. L-Day was set for April 1, 1945. The United States' Field Army, commanded by LtGen Buckner, divided it into two corps, the III Amphibious Corps consisting of 1st, 2nd and 6th Marine Divisions; and the Army's XXIV Corps consisting of the 7th, 77th and 96th Infantry Divisions.

Although the conflicts on Okinawa only lasted for three-plus months vice the five months for Guadalcanal, it proved to be one of the longest and most costly operations in the Central and South Pacific, involving six divisions and almost six times the naval shipping of Guadalcanal. The US Navy lost on average of one-and-a-half ships daily, also making it the costliest naval involvement in the history of sea warfare.

Night offensive action by the amphib recon Marines, not the normal practice during the earlier actions of World War II, was emphasized during the Okinawan campaign as the Marines conducted 21 night patrols and attacks, 13 of which were by the Amphibious Reconnaissance Battalion.

For its last actions on Okinawa, the FMF Amphib Recon Battalion returned to Pearl Harbor on September 12. Five days later, the battalion was disbanded and the bulk of its troops were sent to the replacement battalion at Pearl Harbor. The majority of them left for the United States aboard the LST 761.