Look no further than One Man’s Hero, a 1999 historical war drama that brings to life the remarkable story of the San Patricios, a group of Irish Catholic immigrants who defected from the U.S. Army to fight for Mexico during the Mexican-American War (1846-1848).
This film, directed by Lance Hool, offers a gripping portrayal of loyalty, faith, and sacrifice.
Below, we dive into the movie’s details, answer key FAQs, and explore related topics like the One Man’s Hero cast, St Patrick’s Battalion song, and St Patrick’s Battalion flag.
What is the Movie About the Irish Fighting for Mexico?

Is One Man’s Hero Based on a True Story?
Yes, One Man’s Hero is based on a true story. The film dramatizes the real-life events of the Saint Patrick’s Battalion, a unit of primarily Irish Catholic immigrants who deserted the U.S. Army to fight for Mexico.
Led by John Riley, the battalion was formed due to religious persecution, anti-immigrant sentiment, and promises of land and citizenship from Mexico.
While the movie takes some creative liberties, such as adding a romantic subplot, it remains rooted in historical events, as detailed in sources like Michael Hogan’s book, The Irish Soldiers of Mexico. For more on their motivations, read Why Did the Saint Patrick’s Battalion Change Sides and Fight for Mexico?.
Is One Man a True Story?
The question “Is One Man a true story?” likely refers to One Man’s Hero. As noted, the movie is indeed based on the true story of the Saint Patrick’s Battalion.
John Riley and his men were real figures who fought valiantly in battles like Monterrey and Churubusco. However, the film includes fictional elements, such as Riley’s romance with Marta (Daniela Romo), to enhance the narrative.
Despite these additions, the core story of the San Patricios’ defection and their role in the Mexican-American War is historically accurate.
Key Details About One Man’s Hero
One Man’s Hero Cast
The One Man’s Hero cast includes notable actors like Tom Berenger as John Riley, Joaquim de Almeida as Mexican rebel leader Cortina, Daniela Romo as Marta, and Patrick Bergin as General Winfield Scott. Supporting roles feature James Gammon as General Zachary Taylor and Mark Moses as Colonel Benton Lacey, delivering compelling performances that bring depth to this historical drama.
St Patrick’s Battalion Song and Lyrics
The St Patrick’s Battalion song by David Rovics, titled “Saint Patrick Battalion,” captures the spirit of the San Patricios. The Saint Patrick’s Battalion lyrics reflect their motivations, with lines like: “From Dublin City to San Diego / We witnessed freedom denied / So we formed the Saint Patrick Battalion / And we fought on the Mexican side.” This song, available on albums like Living In These Times, is a powerful tribute to their legacy.
St Patrick’s Battalion Flag
The St Patrick’s Battalion flag was a symbol of the group’s Irish heritage and Mexican allegiance. Described by John Riley, it was green silk with a harp, shamrock, and the motto “Erin Go Bragh” on one side, and an image of St. Patrick on the other, alongside “Libertad por la Republica Mexicana.” This flag, recreated for the film, is a potent emblem of their dual identity.
What Happened to the San Patricios After the War?
What happened to the San Patricios after the war? After the Battle of Churubusco in 1847, most San Patricios were captured. Fifty were hanged in one of the largest mass executions in U.S. history, ordered by General Winfield Scott, despite international protests. John Riley, who deserted before the war’s official start, was spared execution but received 50 lashes and was branded with a “D” for deserter. Some survivors integrated into Mexican society, receiving land grants, while others faced hardship or death. Mexico honors them as heroes, with annual commemorations on September 12.
St Patricks Battalion Documentary
While no major St Patricks Battalion documentary exists, the story has been covered in historical works and short segments. For a deeper dive, check out books like The Irish Soldiers of Mexico or online resources exploring the San Patricios and the Mexican-American War.
One Man’s Hero DVD
Fans can find One Man’s Hero DVD on platforms like Amazon, though availability may vary by region (e.g., Region 1 for the U.S.). Check for widescreen editions to enhance the viewing experience of this visually striking film.
Why Watch One Man’s Hero?
One Man’s Hero is a must-watch for history buffs and those interested in Irish and Mexican heritage. It sheds light on a lesser-known chapter of the Mexican-American War, offering a perspective on the San Patricios’ bravery and sacrifice. Whether you’re curious about the Saint Patrick’s Battalion movie or seeking the One Man’s Hero DVD, this film delivers a poignant narrative of courage and identity.
Ready to explore more? Learn about the San Patricios’ motivations at Secret Ireland.