Hi! don't know if you're still interested, but I may have some information on John Light. I'm trying to research him myself. From old family papers, I have that John light and his wife Barbara came to Pa. from England in the 1700's (date uncertain) and settled in Lancasterco. They had three children; Barbara, David and Elizabeth, born 1786, died in Pittsburgh 1863. Elizabeth married Frederick Warner of Lancaster. She was a gg granddmother on my mother's mother's side. John Light was a methodist Preacher and died at an advanced age in Beaver Pa.
I haven't researched the Lights, but based on the chronology , I would think John was in the Revolutionary war unless he was some form of Militia. He must have been born around 1760 or before. His wife Barbara died in 1788, probably in childbirth, which is why he moved to Beaver county.
Don't know if it is the right Lights. Name and places do seem to match. If it is the one and if he was a Dragoon and forage master, it may have been the War of 1812, but he would have likely been in his 50's or older, so I don't know.