Japanese American units of World War II

When Japanese warplanes attacked Oahu on December 7, 1941, about 2,000 Americans of Japanese ancestry (AJAs) were on Army active duty in Hawaii. Hundreds more were University of Hawaii ROTC cadets who answered the call to arms that day with the Hawaii Territorial Guard.

At the time, Hawaii’s population was about 425,000, and Japanese were the largest ethnic group. Three-fourths of them were U.S.-born citizens, or Nisei.

The shock of Pearl Harbor bred wild rumors that local Japanese aided the enemy. The official history “Hawaii’s War Years” later concluded: “Despite the beliefs to which some people still cling, all the investigative agencies are agreed that espionage in Hawaii before the war was carried on only by the Japanese consular staff and one other person, a German. They also agree that there was no espionage after the start of the war, no sabotage, no fifth column activity of any sort.”

Immediately after Pearl Harbor, however, fear and suspicion ruled. More than 110,000 Japanese were removed from the West Coast and locked up. In Hawaii, more than 1,500 were arrested and relocated. For two years, AJAs were reclassified by Selective Service officials as “enemy aliens” and not eligible for the draft, although they were allowed to volunteer for racially segregated units. The Navy and Marine Corps did not enlist Nisei during the war, but made wide use of them in the Pacific.

In World War II, these units were made up primarily of AJAs:

• 100th Infantry Battalion: A year before Pearl Harbor, America began drafting men for the military and activating National Guard units. As a result, about half of Hawaii’s newly federalized 298th and 299th Infantry regiments were AJA draftees or volunteers. In May 1942, these 1,400 Nisei were removed from their units and organized into a separate battalion. During the Battle of Midway, they were sent from Hawaii to Camp McCoy, Wisconsin. They became the 100th Infantry Battalion (Separate) and adopted the motto, “Remember Pearl Harbor.” After more than a year, the 100th was sent to North Africa and then Italy, entering combat near Salerno in September 1943. Attached to the 34th Infantry Division, the 100th earned respect and the nickname “The Purple Heart Battalion,” in fierce fighting at the Rapido River and Monte Cassino. The battalion received replacements of Hawaii and Mainland AJAs from the 442nd Regimental Combat Team, which arrived in Italy in June 1944. The 100th became the combat team’s first battalion and fought with the larger unit in Italy, France and again in Italy. The 100th maintained its unique designation and identity and earned three Presidential Unit Citations. Today’s 100th/442nd is the Army Reserve’s only combat arms unit.

• Military Intelligence Service: About 6,000 AJAs – roughly half of them from Hawaii – served with the Army’s Military Intelligence Service in the war against their parents’ homeland or in the postwar occupation. Armed with knowledge of the enemy’s language and customs, they served as interpreters, translators, POW interrogators, propagandists, electronic eavesdroppers, spies, guerilla leaders, cave flushers, and combat infantrymen. Most, but not all, trained at the MIS Language School in Minnesota. Beginning with Guadalcanal in 1942, MIS AJAs fought in every major battle in the war against Japan. They served with every major U.S. and Allied command in the Pacific and Asia. They often risked being mistaken for the enemy and shot by fellow GIs. The MIS Nisei were credited with saving countless lives and shortening the war. Afterward, MIS Nisei served in every phase of the occupation of Japan, from monitoring the populace, interpreting at war crimes trials, censoring the press and films to building a © Mark Matsunaga, PHP, August 10, 2016 2 new government. They helped both sides bury wartime hatreds and did much to create the modern democracy that emerged from the ashes of Imperial Japan. Their work went unheralded for years because of its classified nature and the lack of records that resulted from the fact that MIS Nisei usually served individually or in small detachments attached temporarily to larger units. The MIS received a Presidential Unit Citation in 2000.

• 442nd Regimental Combat Team: Six weeks after Pearl Harbor, the Hawaii Territorial Guard dismissed all of its Nisei members. Rather than accept rejection, 169 of them organized as the Varsity Victory Volunteers and performed manual labor for the Army for nearly a year, hoping to earn a chance to fight. In light of the VVV’s work and the excellent record of the Nisei of the MIS and 100th Battalion, the War Department in early 1943 called for volunteers for a 4,500-man AJA regimental combat team. Nearly 10,000 volunteered from Hawaii. Only 1,200 initially volunteered from the Mainland, where most Japanese Americans had been locked up. The 442nd trained in Mississippi (and provided 250 men to the MIS), then deployed in mid-1944 to Anzio in Italy. There, the 442nd joined and absorbed the100th Battalion. The combat team consisted of the 442nd Infantry Regiment (100th, 2nd and 3rd battalions), 522nd Field Artillery Battalion, 232nd Combat Engineer Company, 206th Army Band and cannon and anti-tank companies. The 442nd fought gallantly in Italy and in France, where it rescued the “Lost Battalion” of the 141st Infantry Regiment. Near the war’s end, the combat team, minus its artillery battalion, returned to Northern Italy, where it broke through the final German line of resistance. The 522nd was assigned to the Seventh Army’s final push through southern Germany and liberated Nazi concentration camp inmates from the Dachau death march. The 442nd RCT was the most-decorated unit in U.S. history for its size and length of service. It earned seven Presidential Unit Citations, including the three earned by the 100th Battalion. Twenty-one members of the 100th and 442nd received the Medal of Honor.

• 1399th Engineer Construction Battalion: More than 1,000 AJAs served in the 1399th, which remained in Hawaii during the war, building 54 major military projects in America’s “Gibraltar of the Pacific.” A plan to deploy the unit in the Philippines was vetoed by the War Department, because its work in Hawaii was deemed too valuable and because of an Army policy that barred AJAs other than intelligence specialists from combat areas in the Pacific. The 1399th earned a Meritorious Service Award in 1945.

Ethnic Japanese made up 37 percent of Hawaii’s 1940 population. The final World War II tally found AJAs made up more than 62 percent of the 806 Hawaii residents killed in service to America.

In July 1946, President Harry Truman greeted the 442nd RCT on the White House lawn to present its final Presidential Unit Citation. He said, “You fought not only the enemy, but you fought prejudice, and you have won. Keep up that fight, and we will continue to win--to make this great Republic stand for just what the Constitution says it stands for: the welfare of all the people all the time.” Two years later, Truman ordered an end to racial segregation in the military.

Nisei veterans came home to help change the nation and Hawaii, where they helped to open Island society and overcome political obstacles to statehood. Those veterans included U.S. Senators Daniel Inouye (442nd ) and Spark Matsunaga (100th) and Governor George Ariyoshi (MIS).

© Mark Matsunaga, PHP, August 10, 2016

Last updated: May 2, 2018

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