Hawaii's 100th Infantry Battalion Separa​​​te was the first U.S. Army combat unit​ composed of Americans of Japanese ancestry (AJAs). Its original members had been inducted into the Army before Japanese planes swept down on Pearl Harbor, December 7, 1941. How the loyalty of these soldiers was questioned by other Americans, then put to the test, and finally proved beyond doubt on the battlefields of Europe is the subject of this book.

Sometimes called the Purple Heart Battalion because of its casualty lists, the 100th established a record in Italy and France that made it one of the most decorated units in the history of the U.S. Army. Describing the Italian campaign General Mark W. Clark wrote: "I should mention here that a bright spot in this period was the performance of the 100th Battalion . . . it fought magnificently. . . . These Nisei troops seemed to be very conscious of the fact that they had an opportunity to prove the loyalty of many thousands of Americans of Japanese ancestry and they willingly paid a high price to achieve that goal. I was proud to have them in the Fifth Army."

While the book is primarily about the young AJAs, there is another group of men who should be remembered. After Pearl Harbor, when thousands were clamoring for wholesale evacuation and internment of all Japanese Americans, a few individuals refused to doubt "because it would belittle the value of our American institutions." Speaking of one of these men of faith [Charles R. Hemenway], the editor of the Hawaii Herald wrote, "We were at the crossroads in that terrible December and it was largely due to (his) courage and influence that Hawaii took the right turn instead of the wrong. . . . The entire community and the nation owe him a debt of gratitude for his part in persuading us that we were justified in trying out the democratic ideals we had professed."

Ambassadors in Arms, then, is a story not only of loyalty and courage but of faith.