Shortly after his birth, his family moved to Chicago after his father was put in charge of Fort Dearborn.

After arriving in Florida, McNeil and his unit were stationed at Fort Picolata, where they were put under the command of General Joseph Marion Hernández.

A Seminole defector named Tomoka John was attached to McNeil's unit as their Indian guide.

On September 10, 1837, Tomoka John led Lieutenant McNeil and his soldiers to a hostile Miccosukee village near Mosquito Inlet.

McNeil died of his bullet wound the next day on September 11, 1837, during his unit's march back to St. Augustine.