Suvarna Garge (Editor)

100th Infantry Battalion (United States)

Updated on
Share on FacebookTweet on TwitterShare on LinkedInShare on Reddit
Active  1942–1946 1947–present
Garrison/HQ  Fort Shafter
Branch  United States Army
100th Infantry Battalion (United States)

Allegiance  United States of America
Type  Separate infantry battalion
Nickname(s)  "Purple Heart Battalion" "One-Puka-Puka"

The 100th Infantry Battalion is the only infantry unit in the United States Army Reserve. In World War II, the then-primarily Nisei battalion was composed largely of former members of the Hawaii Army National Guard. The 100th saw heavy combat during World War II before and after combining with the 442nd Infantry Regiment, another mostly Nisei military unit, into a single fighting combat team. Based at Fort Shafter, Honolulu, Hawaii, the 100th Battalion has reservists from Hawaii, American Samoa, Guam and Saipan, and has deployed to Iraq and Kuwait. The unit was unofficially nicknamed the "Purple Heart Battalion", with the motto "Remember Pearl Harbor".



On the morning 7 December 1941, the United States was attacked by the Empire of Japan, marking the beginning of World War II for the United States. After the attack, Japanese-Americans and those of Japanese descent faced prejudice at home. Chaos ensued in the hours that followed the Pearl Harbor attack, but the 298th and 299th Hawaii National Guard prepared for an invasion, cleared the rubble, donated their blood, and aided the wounded. However, three days after the attack, the units' rifles were stripped from them because of the ethnicity of members; eventually those rifles were returned. Nisei that were a part of the ROTC program at the University of Hawaii were discharged from the Hawaii Territorial Guard. Those former members eventually formed the Varsity Victory Volunteers.

At 11:30 a.m. martial law was declared and Governor Joseph Poindexter told President Franklin D. Roosevelt that his greatest fear was sabotage by the large Japanese population in Hawaii. The FBI rounded up known Japanese sympathizers, Buddhist priests, language school principals and teachers, civic and business leaders, fisherman, and instructors of judo and related martial arts. The War Department discharged all soldiers of Japanese ancestry, had all Japanese-Americans on the West Coast rounded up and placed in internment camps around the U. S., deactivated of the Hawaii Territorial Guard, and had all Japanese-Americans reclassified as 4-C: enemy aliens.

History says General Delos Emmons, appointed military governor on 17 December, supported placing Japanese-Americans in internment camps and having them reclassified as enemy aliens, but in actuality he wanted to give them a chance to prove their patriotism. After General Emmons agreed to let the Varsity Victory Volunteers form, a confidential memo was sent to the War Department in early April 1942 stating that there were 2,000 Japanese-American soldiers now serving and many more who wished to serve to demonstrate their loyalty to the United States. Their desire was to organize into a fighting force to be sent to Europe or Africa to fight the Germans and Italians; that request was later denied by the War Department.

Formation of the 100th Battalion

As Battle of Midway was well underway, on 4 June 1942 1,432 Nisei of the Hawaii National Guard had their weapons taken away and boarded the U.S. Army transport USAT Maui, formerly a Matson liner, under the cover of night and shipped to the mainland without saying goodbye to their family or loved ones. Under the title "Hawaiian Provisional Infantry Battalion" the week-long zig-zag journey took them to a port in Oakland where they were designated the 100th Infantry Battalion on 12 June 1942. The unit number was an indication of the Army's recently formulated plan for a modern organization for the Combat Arms. Under normal pre-war Army procedures, all infantry battalions were organic to the regiment they were a part of, and were known as, for instance, "1st Battalion, 5th Regiment." With the new system of organization, the infantry regiment was reorganized as a headquarters with no organic battalions, but with three separate battalions attached. The headquarters was organized into three combat commands that could be dispatched on separate combat actions with units that were attached. One Infantry battalion would be assigned to a combat command, with attachments from the higher headquarters reserve. The 100th, however, was not initially attached to a regiment. It came to be unofficially known as the "One-Puka-Puka" (Puka means "hole" in Hawaiian).

Camp McCoy and Camp Shelby

In Oakland, the 100th boarded a train to their final destination, Camp McCoy, Wisconsin. Immediately following their arrival to Camp McCoy many of the Nisei felt animosity and distrust from fellow soldiers and military and political leaders. The 100th was quartered in tents, four soldiers per tent, which contained a bunk bed, blanket, towels, and backpack. It would be several months until the Nisei moved into military barracks. Eventually soldiers were permanently placed into military units, such as Companies A through E, and pushed through physical, marksmanship, and tactical training.

Some of the white officers and NCO's appointed to the 100th were schooled in psychology and were ordered to test their physical and military capabilities but most of all their loyalty. The Nisei competed with other companies in marksmanship, baseball, softball, physical combat such as scuffles, boxing, and wrestling.

On one such occasion that happened to prove the loyalty and bravery of the new recruits, five Nisei soldiers received the Soldier's Medal for their rescue of several local civilians from drowning on a frozen Wisconsin lake.

On one occasion, about 25 of the Japanese-American soldiers were sent to a secret training mission on a small island, Cat Island, near the mouth of the Mississippi River. Some top military officers thought that the "Jap" soldiers smelled differently, and that the Nisei soldiers would give off a similar scent. So for three months these 25 Nisei were ordered to train attack dogs to "smell Japs." The training didn’t work.

Training at Camp McCoy lasted six months until on 6 January 1943 the 100th Battalion was transferred to Camp Shelby, Mississippi. The 100th was attached to the 85th Division under Major General Wade Haislip and would receive even tougher training than they did at Camp McCoy. Upon arrival at Camp Shelby the 100th received the same amount of skepticism as they did at McCoy. The 100th successfully passed the training exercises. At Camp Shelby where 100th received its most intense and advanced training and then was sent to Camp Clairborne, Louisiana for field exercises and war games.

On return from Camp Clairborne, the 100th met up with the newly formed 442nd Regimental Combat Team on 16 July. On 20 July 1943 the 100th received its battalion colors and motto, "Remember Pearl Harbor," as requested by the unit.

Africa and Italy

After training at Camp McCoy, Wisconsin, and Camp Shelby, Mississippi, the battalion was ready to deploy, but was refused by General Dwight D. Eisenhower. Lieutenant General Mark Wayne Clark, commanding the United States Fifth Army, accepted the offer, and the 100th deployed from Shelby on 11 August by train to Camp Kilmer, New Jersey and then to the Mediterranean on 20 August 1943.

The 100th arrived in Oran, North Africa on 2 September 1943 and became a part of the 133rd Infantry Regiment under the 34th Infantry Division and took part in training with Caucasian soldiers. On 19 September the 34th Division sailed from Africa to southeast of Naples, with the 100th with them.

The unit were to fight in the Italian Campaign and entered combat on 29 September 1943, near Salerno in Southern Italy. The unit advanced 15 miles (24 km) in 24 hours for a week against strong enemy resistance which allowed them to take Benevento, an important rail center and road intersection. The 100th crossed the Volturno River three times, taking on heavy German machine gun fire and rocket launchers before driving the German force even further north.

Monte Cassino

At the top of Monte Cassino stood a grand but old monastery, a key target for the 5th Army. To take the Gustav Line, the Allies would have to descend into the Rapido River valley, traverse two miles of open fields filled with landmines, mud, and knee-deep cold water, cross a swift-moving river, and barbed wire and up the steep, rocky slopes, to the 1500-foot peak of Monte Cassino. From there they would have to ascend still higher to a four-story fortress, with 10-foot-thick stone walls. This was the St. Benedictine monastery. The battle commenced in January. Here they earned their nickname the "Purple Heart Battalion." At night, A and C companies passed their way through the river reaching the wall where the enemy was located and held their ground under intense fire into the next day. B Company was met with heavy machine gun fire as their cover by the smoke screen was blown away leaving only 14 of the original 187 men in B Company to reach the wall.

The three companies were immediately pulled back to San Micheli the next night. The 100th then was ordered to take Castle Hill, which they did on 8 February. The hill was held for four days dealing with not only machine gun fire but tanks as well. The hill was a key location for it was close to the monastery but the 34th Division's right and left flanks were unable to hold their positions because of heavy German resistance. The 100th was again ordered back.

After three days of bombing, the second assault commenced. In one platoon of the 100th only five of forty soldiers survived. The 100th again was pulled back into reserve and replaced by British and Indian soldiers after nearly taking Cassino. War correspondents calling the 100th's soldiers "little men of iron" and the "purple heart battalion." This would be the last time Nisei of the 100th would see combat at Monte Cassino as they were taken back to San Michele to rest and reorganize. It would be here where replacements from the 442nd would come in to replenish the 100th's ranks.

There were over 50,000 allied casualties in the battle. Casualties took the 100th's numbers from 1300 5 months prior to nearly 500. Cassino didn't fall unit 17 May. After Cassino, the 100th began to receive its first replacements from the 442nd. It is argued that the heavy losses were because of members of the U.S. War Department neglecting the Italian campaign by taking men and supplies away and putting it towards the coming invasion of Normandy. The battalion was later awarded the Distinguished Unit Citation (DUC) [later redesignated the Presidential Unit Citation (PUC)] for its actions on 26–27 June.

Anzio, Rome, and the 442

Following Monte Cassino, the 100th was soon deployed at the Anzio beachhead on 26 March 1944. The allies held a beachhead that spanned 15 miles (24 km) inland going a few miles inland. The battlefield at Anzio was very similar to battlefields in World War I as there was a large stretch of land between both opposing forces declared as "No Man's Land" and both sides didn't go on a large-scale offensive. The sides only fought at night. During the day, soldiers slept. The fall of Monte Cassino finally led to the end of the stalemate on 17 May 1944. Ont 23 May the allies went on the offensive to drive the Germans north. However, the allies needed more information about the enemy, so the 100th was ordered to capture a German soldier. Lieutenant Young-Oak Kim, a Korean American born in Los Angeles, California, and Nisei PFC Irving Akahoshi from the 100th volunteered for the mission and captured two German soldiers. On the push to Rome, Lanuvio, the final German stronghold, fell to the 100th Infantry Battalion.

"We had been sitting and living in foxholes at Anzio some 63 days. Then the big push out and the capture of Rome. They (100th Battalion) wiped out the last heavy German resistance we met some 12 miles south of Rome and then it was practically a walk into the city."

The 100th was ordered to stay at the roadside on 4, 10 June kilometers from Rome and watched other troops march by. They never saw Rome. Instead, the 100th was taken 40 miles (64 km) northwest of Rome to Civitavecchia where on 11 June 1944, the 100th was attached to the newly arrived 442nd Regimental Combat Team. Because of its combat record, the 100th was allowed to keep their original designation, giving the newly formed all-Nisei fighting unit the name 100th/442nd Regimental Combat Team under the 34th Division.


The nation's highest award for combat valor, the Medal of Honor, was conferred upon twenty-one members of the 100th Infantry battalion of the 442nd Regimental Combat Team of World War II.

On 5 October 2010, the Congressional Gold Medal was awarded to the 442nd Regimental Combat Team and the 100th Infantry Battalion, as well as the 6,000 Japanese Americans who served in the Military Intelligence Service during the war.

In 2012, the surviving members of the 442nd RCT were made chevaliers of the French Légion d'Honneur for their actions contributing to the liberation of France during World War II and their heroic rescue of the Lost Battalion outside of Biffontaine.

Lineage following World War II

  • Inactivated 15 August 1946 at Honolulu, Hawaii
  • Allotted 27 March 1947 to the Organized Reserves
  • Activated 31 July 1947 with headquarters at Fort DeRussy, Hawaii
  • Organized Reserves redesignated 25 March 1948 as the Organized Reserve Corps;
  • Organized Reserve Corps redesignated 9 July 1952 as the Army Reserve
  • Reorganized and redesignated 29 May 1959 as the 100th Battle Group, 442d Infantry
  • Reorganized and redesignated 1 May 1964 as the 100th Battalion, 442d Infantry
  • Ordered into active military service 13 May 1968 at Fort DeRussy, Hawaii;
  • Released from active military service 12 December 1969 and reverted to reserve status
  • Location of Headquarters changed 1 September 1994 to Fort Shafter, Hawaii
  • Ordered into active military service 16 August 2004 at Fort Shafter, Hawaii
  • Redesignated 1 October 2005 as the 100th Battalion, 442d Infantry Regiment
  • Released from active military service 13 March 2006 and reverted to reserve status
  • Campaign participation credit

  • World War II:
  • Naples-Foggia;
  • Anzio;
  • Rome-Arno;
  • North Apennines;
  • Rhineland;
  • Po Valley
  • War on Terrorism:
  • Iraq
  • Decorations

  • Presidential Unit Citation (Army) for BELVEDERE
  • Presidential Unit Citation (Army) for BIFFONTAINE
  • Presidential Unit Citation (Army) for FRANCE AND ITALY
  • Presidential Unit Citation (Army) for GOTHIC LINE
  • Meritorious Unit Commendation (Army) for IRAQ 2005–2006
  • References

    100th Infantry Battalion (United States) Wikipedia