[2] Most of The Fighting 69th was filmed at Warner Brothers' Calabasas Ranch location, which served as Camp Mills, the regiment's training base, various French villages, and numerous battlefields.

[3] The plot centers on misfit Jerry Plunkett (James Cagney), a tough-talking New Yorker who displays a mixture of bravado and disrespect for officers.

Caught up in patriotic fervor when the United States enters WWI, he joins the 69th with aim of winning medals by singlehandedly defeating the Germans.

The chaplain, Father Francis P. Duffy (Pat O'Brien) believes there to be something more in the young man and begs the 69th's commanding officer Major "Wild Bill" Donovan (George Brent) to give Plunkett one more chance.

While Jerry Plunkett was a fictional character, Father Duffy, Major Donovan, Lt. Ames, and poet Joyce Kilmer were all real members of the 69th.

Many of the events depicted (training at Camp Mills, the Mud March, dugout collapse at Rouge Bouquet, crossing the Ourcq River, Victory Parade, etc.)

[4][5] Priscilla Lane was initially cast as one of the soldiers' girls back home, but the part was cut prior to production.