Lt. Gen. Hugh Swayne was the son of John Swayne and Elizabeth Uniacke from Youghal, Cork, Ireland. Most of his military record is an easy find through a google search because he was once administrator of Cape Breton in Canada. He died in Paris, France in 1836.
However, there appears to be some discrepancy on his birth date. His death record says he was 64, giving him a birth date of 1772. However, he was appointed a 2nd Lieutenant in Apr 1782, which would mean he was 10 years old at the time. His parents were married 25 May 1765, and he was the eldest son, so giving him a birth date of 1766 would mean he was only 16 when he was made a 2nd Lieutenant.
I am not an expert on the military during this time period, but was normal for a 16 year old to be made a 2nd Lieutenant that young or was it unusual?