The Cassidy story

History isn't just something I read about. It's something I inherited.

I am Shaun Cassidy of San Diego, California, a descendant of Thomas Cassidy, one of the Irish soldiers who served in the Saint Patrick's Battalion. The San Patricios during the Mexican American War.

Growing up, I knew my family carried an Irish name, but it took years to fully understand the extraordinary story behind it.

Thomas Cassidy was one of thousands of Irish immigrants who came to America seeking opportunity. Instead, he found himself caught in a war that tested not only his loyalty, but his conscience.

Like many Irish immigrants serving in the U.S. Army, Thomas experienced anti-Irish and anti-Catholic prejudice.

During the war with Mexico, he made the difficult decision to join the San Patricios, a battalion made up largely of Irish immigrants who believed they could not, in good conscience, fight against another Catholic nation. It was a choice that cost many of them everything.

Thomas Cassidy was captured after the Battle of Churubusco and died wearing a Mexican uniform. In the United States, the San Patricios were long remembered as traitors. In Mexico, they are honored as men of courage and conviction who stood with a nation under invasion.

As his descendant, I have spent years helping tell their story because I believe history deserves to be complete, even when it is complicated.

Living in San Diego, where the United States and Mexico meet every day through families, culture, and shared history, I see echoes of the San Patricios' story all around me.

The border is not simply a dividing line. It is a place where identities overlap, where people build lives across cultures, and where questions of belonging continue to matter.

My family's story has inspired my own commitment to preserving the history of the San Patricios and to promoting understanding between Ireland, Mexico, and the United States.

I believe the legacy of Irish America is not only found in politics, business, or military service, but also in the courage to stand by one's principles and to recognize our common humanity.

The story of Thomas Cassidy reminds me that Irish identity has never been one-dimensional.

It is a story of migration, hardship, resilience, faith, and moral conviction. Those values continue to shape who I am today.

When I tell people about the San Patricios, I am not trying to reopen old debates. I am honoring an ancestor whose life reminds us that history is made by imperfect people facing impossible choices.

I carry the Cassidy name with pride, not because of what my ancestor achieved, but because of the values his story represents: compassion, conviction, and the willingness to stand for what he believed was right.

His story is part of Ireland's story.

It is part of America's story.

And it is part of mine.