Hamilton, the first Treasury Secretary who has garnered renewed attention in recent years due to the hit Broadway musical that bears his name, wrote the letter to the Marquis de Lafayette, the French aristocrat who served as general in the Continental Army.
Dated July 21, 1780, it details an impending British threat to French forces in Rhode Island.
“We have just received from New York through various channels the advice that the enemy is making an embarkation with which he threatens the French fleet and army,” wrote Hamilton. “Fifty transports would have come up the Sound to pick up troops and go straight to Rhode Island.”
It is signed “Yr. Most Obedt, A. Hamilton, aide-de-camp.
The letter was forwarded by Massachusetts General William Heath to heads of state, along with a request for troops to support French allies, Galvin’s office said.
The letter was allegedly stolen during World War II by an employee of the state archives and then sold to a private individual.
It resurfaced several years ago when an auctioneer in Virginia received it from a family who wanted to sell it. The auction house determined it was stolen and contacted the FBI. A federal appeals court ruled in October that it was state-owned.