Marine Corps Historical Collection
The successful battle for both ends of Kwajalein Atoll had been concluded, and a series of conclusions were drawn from it. Japanese deaths reached a total of 8,122, some 27 times the number of Americans killed. The relatively small scale of U.S. casualties gave Admiral Chester W. Nimitz the ready forces he needed to push forward rapidly with plans for further action: first, one more atoll in the Marshalls, and then quickly on to the vital Mariana Islands, the linchpin of Japan’s inner line of defense. Kwajalein would provide the air base from which the B-29 bombers would conduct their raids on the Marianas, and the Army 7th Infantry Division and the 4th Marine Division would play key roles in those future operations.
Tactically, there were a variety of innovations in the twin battles at Kwajalein, and these would continue to prove valuable in the future. There was the first use of Navy underwater demolition teams; the first use of DUKWs in combat; the first use of command ships with special communications equipment to control the battle; the first use of airplanes to control naval gunfire; and the first use of armored amphibian tractors (LVTAs). In addition, the two battles saw the debut of new units designed to facilitate crucial communications during combat. These were the Joint Assault Signal Companies. The official Marine history of the Marshalls campaign described their complex responsibilities:
The primary mission of this unit was to coordinate all supporting fires available to a Marine division during an amphibious operation. In order to carry out this function, the company was divided into Shore and Beach Party Communications Teams, Air Liaison Parties, and Shore Fire Control Parties.... During training, the various teams were attached to the regiments and battalions of the division. Thus each assault battalion could become familiar with its shore and beach party, air liaison, and fire control teams.
Another new element was the way rockets were used. This was a centuries-old technique of bombardment, but in the Marshalls the 4th Marine Division was the first American division to use rockets mounted on jeeps, pick-up trucks, and Navy gunboats in combat.
One other Marine resource was unique: the use of Navajo Indian “code talkers” in battle. They proved a perfect foil for the Japanese ability in previous battles to understand Marine voice-to-voice communications and Morse Code. To prevent this a group of Navajo Indians had been recruited and trained in special code words they could use in combat. When they were talking in the Navajo’s exotic language, no Japanese would ever decipher the message! At Roi-Namur their walkie-talkie portable radios carried the urgent instructions back and forth between ship and shore, as well as between higher echelons and subordinate units, and did it so quickly that previous delays of up to 12 hours (intercepting, transmitting, and deciphering messages) were eliminated.
Finally, the two battles for Kwajalein Atoll proved incontestably the effectiveness of prolonged and massive preinvasion naval gunfire and aerial bombing. The U.S. planes and warships had so thoroughly scoured not only the target islands, but also the other Japanese air bases in the Marshalls, that not a single Japanese plane was able to attack the American surface forces in the campaign.
Department of Defense Photo (USMC) 70200