The 442nd Infantry Regiment was an infantry regiment of the United States Army. The regiment including the 100th Infantry Battalion is best known as the most decorated in U.S. military history, and as a fighting unit composed almost entirely of second-generation American soldiers of Japanese ancestry (Nisei) who fought in World War II. Beginning in 1944, the regiment fought primarily in the European Theatre, in particular Italy, southern France, and Germany. The 442nd Regimental Combat Team (RCT) was organized on March 23, 1943, in response to the War Department's call for volunteers to form the segregated Japanese American army combat unit. More than 12,000 Nisei volunteers answered the call. Ultimately 2,686 from Hawaii and 1,500 from mainland U.S. internment camps assembled at Camp Shelby, Mississippi in April 1943 for a year of infantry training. Many of the soldiers from the continental U.S. had families in internment camps while they fought abroad. The unit's motto was "Go for Broke".

Nisei is a Japanese-language term used in countries in North America and South America to specify the ethnically Japanese children born in the new country to Japanese-born immigrants. The Nisei are considered the second generation and the grandchildren of the Japanese-born immigrants are called Sansei, or third generation. Though nisei means "second-generation immigrant", it often refers to the children of the initial diaspora, occurring in the late 19th and early 20th centuries, and overlapping with the G.I. and silent generations.