Saint Patrick's Battalion Remembrance Day in Mexico Date in the current year: September 12, 2024

The Saint Patrick's Battalion was formed by John Riley and Patrick Dalton. It originally consisted of Catholic Irish and German immigrants who had defected or deserted from the U.S. Army. Later, other immigrants of different descent and escaped slaves also joined the battalion. There were only a few actual U.S. citizens in the ranks.

The San Patricios participated in many major battles during the Mexican-American War. Many of them were captured during the Battle of Churubusco (1847). They were tried for desertion and sentenced to death by hanging. Fifty battalion members were hanged between September 10 and 13, 1847.

The members of the Saint Patrick's Battalion are commemorated twice a year, on September 12 and March 17. September 12 is the generally accepted anniversary of their executions, and March 17 is Saint Patrick's Day. September 12 is not an official memorial day, but it is still observed in many cities and towns.