McGrath of Harlow, many Tories fled or were driven to Canada during and after the Revolutionary War. New York City was occupied by British forces during most of the War (with many instances of brutal treatment) and Tories were not very welcome afterwards.

You would be interested to read Irish Green & Union Blue: The Civil War Letters of Peter Welsh. Peter Welsh was born in Charlottetown, Prince Edward's Island, Canada and immigrated to the United States. He married in Boston and enlisted in a regiment of Meagher's Irish Brigade of the Union Army. Having survived 3 very hard battles in which the Brigade was chewed up horribly (Antietam, Fredericksburg and Gettysburg), he re-enlisted in 1863. He did not make it through to the end and he is buried in New York City. I assure you that there are people who leap into the cauldron as well as out of it.

All the best,
Dan