A Nisei US Army unit in Italy was said to have had the highest percapita decorations for bravery in the whole Army
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The 100th/442nd and no "said" about it. They were the most highly decorated unit in the Army in WWII. Any Texans who served were very glad to see those Japanese faces after the 442nd fought up hill, enduring heavy casualties to relieve the surrounded Texans.
From a site found after a loooong search:
President Clinton Approves Medal of Honor for 100th/442nd World War II Heroes

The Americans of Japanese Ancestry WWII Memorial Alliance late last week received a formal notice from Washington D.C. that President Clinton approved awarding members of the 100th Battalion and 442nd Regimental Combat Team the nation's highest decoration, the Congressional Medal of Honor, for action during World War II, announced President Roy Machida.

The total of twenty-one Asian American recommendations were made by Secretary of the Army Louis Caldera following a careful review by the Army of the war records of those Asian Pacific American veterans whose World War II bravery at the time earned them the award of the Distinguished Service Cross, the nation's second highest award. The review of the records of the Asian Pacific American veterans by the Army and the Navy was authorized by the 1996 Defense Authorization Act to ensure wartime conditions had not led to such bravery being inadequately recognized. Senator Daniel Akaka of Hawaii authored the specific provision to ensure that the veterans valorous actions could be considered notwithstanding statutory time restrictions for considering such awards. While 104 Asian Pacific Americans were awarded the Distinguished Service Cross for actions during World War II, only two were awarded the Medal of Honor.

Nineteen of the 21 Asian Pacific American veterans are Japanese Americans of the celebrated 100th Battalion/442nd Regimental Combat Team, the most highly decorated unit in the history of the U.S. armed forces.The unit earned over 18,000 individual decorations, including 9,486 Purple Hearts and seven Presidential Unit Citations, the nation's top award for combat units. The 100th/442nd's famous motto, "Go For Broke,"reflects its reputation for accomplishing its mission despite all costs. Many of the Japanese Americans who served in the 100th/442nd volunteered from internment camps where their families had been relocated after the outbreak of the war. .

The 100th/442nd fought in eight major campaigns in Italy, France and Germany, including battles at Monte Cassino, Anzio, and Biffontaine, where they arguably fought their most famous battle, the epic "Rescue of the Lost Battalion,"in which the Japanese American unit sustained over 800 casualties to rescue 211 members of the Texan 1st Battalion of the 141st Regiment. In addition to the 21 approved for the award, a Medal of Honor recommendation for another Japanese American, James Okubo, was favorably considered under a separate provision of law, but cannot be formally approved until Congress waives the statutory time restriction in his specific case. Okubo, an Army medic, received a Silver Star for his actions near Biffontaine in October and November 1944, where he was cited for extraordinary heroism in several separate actions in which he saved the lives of fellow 100th/442nd soldiers while exposing himself to intense enemy fire.

Those who were approved to receive the Medal of Honor are: Davila, Rudolph B., SSgt. (later 2nd Lt.), 7th Infantry, for actions on May 28, 1944, at Artena, Italy. Hajiro, Barney F., Pvt., 442nd Regimental Combat Team, for actions in October 1944 for actions at Bruyeres and Biffontaine, France. Hasemoto, Miko, Pvt., 100th Infantry Battalion (Sep), for actions on November 29, 1943, at Cerasuolo, Italy (Posthumous). Hayashi, Joe, Pvt., 442nd Regimental Combat Team, for actions in April 1945 at Tendola, Italy. Hayashi, Shizuya, Pvt., 100th Infantry Battalion (Sep), for actions on November 29, 1942, at Cerasuolo, Italy. Inouye, Daniel K., 2nd Lt. (later 1st Lt.), 442nd Regimental Combat Team, for actions on April 21, 1945, at San Terenzo, Italy. Kobashigawa, Yeiki, Tech. Sgt., 100th Infantry Battalion, for actions on June 2, 1944, at Lanuvio, Italy. Kuroda, Robert T., SSgt., 442nd Regimental Combat Team, for actions on October 20, 1944 at Bruheres, France (Posthumous). Muranaga, Kiyoshi K., Pfc., 442nd Regimental Combat Team, for actions on June 26, 1944, at Suvereto, Italy (Posthumous). Nakae, Masato, Pvt., 100th/442nd Regimental Combat Team, for actions on August 19, 1944, at Pisa, Italy (Posthumous). Nakamine, Shinyei, Pvt., 100th Infantry Battalion (Sep), for actions on June 2, 1944, at La Torreto, Italy (Posthumous). Nakamura, William K., Pfc., 442nd Regimental Combat Team, for actions on July 4, 1944, at Castellina, Italy (Posthumous). Nishimoto, Joe M., Pfc., 442nd Regimental Combat Team, for actions on November 7, 1944, at La Houssiere, France (Posthumous). Ohata, Allan M., Sgt. (later SSgt.), 100th Infantry Battalion (Sep), for actions in November 1943, at Cerasuoll, Italy. Okutsu, Yukio, Tech. Sgt., 442nd Regimental Combat Team, for actions on April 7, 1945, at Mount Belvedere, Italy. Ono, Frank H., Pfc., 442nd Regimental Combat Team, for actions on July 4, 1944, at Castellina, Italy (Posthumous). Otani, Kazuo, SSgt., 442nd Regimental Combat Team, for actions on July 15, 1944, at Pieve di. S. Luce, Italy (Posthumous). Sakato, George T., Pvt., 442nd Regimental Combat Team, for actions on October 29, 1944, in Biffontaine, France. Tanouye, Ted T., Tech. Sgt., 442nd Regimental Combat Team, for actions on July 7, 1944, at Molina A Ventoabbto, Italy (Posthumous). Wai, Francis B., Capt., 34th, for actions on October 20, 1944, at Leyte, Phillipine Islands (Posthumous).
Another link for history of the regiment :
http://www.katonk.com/442nd/442/page1.html