While researching a book on Alexander Scammell, I came across a remarkable letter in the Founders Online government archive—a relatively recent addition that, until now, has been seen by only a handful of people.The letter was written by General George Washington to a French officer named Armand-Louis de Gontaut Biron, better known as the duc de Lauzun. Washington simply referred to him as "the Duke." Known for his sincerity and restraint in offering praise, Washington rarely complimented anyone unless it was well deserved. That makes this letter all the more powerful.The timing was significant: the long and hard-fought Revolutionary War was drawing to a close, and Washington had just learned that the Duke would soon be returning to France. What follows is the letter, dated May 10, 1783: From George Washington to Armand-Louis de Gontaut Biron, duc de Lauzun, 1783 May 10, 1783 Head Quarters Sir,I now have the honor to inform you, as I previously did the Minister of France, that with peace so close to final conclusion, I could not justify detaining the troops under your command from the expectations of their sovereign, or from their own desire to return to their native country and families.I cannot fail to express, on this occasion, my highest esteem for you, sir, and for all the brave officers and soldiers of your corps. I will always remember their noble contributions to the cause of the United States and to the establishment of our independence as a nation.Your personal service—marked by politeness, zeal, and unfailing attention—has left a deep and lasting impression on me. I would have been greatly satisfied to express these sentiments to you in person, had your orders allowed a longer stay. Still, my regret at parting is softened by your kind hope that we may meet again in America. If so, you can be certain I will welcome the opportunity to show you the particular esteem and attachment with which I have the honor to be, sir, Your most obedient servant, George Washington The Duke replied shortly before leaving America for France: From the duc de Lauzun to George Washington, May 12, 1783Cape May Dear General,I cannot leave America without offering your Excellency my most grateful thanks for the kind and flattering letter you honored me with. The memory of your friendship will forever be dear and glorious to me. Reading these letters compelled me to learn more about “the Duke.” He arrived in America with 500 soldiers he personally helped finance and organize. He sailed from France alongside General Rochambeau, leading a striking unit of impeccably dressed hussars—elite cavalrymen on horseback. These troops would distinguish themselves in several key battles of the Revolutionary War. The Duke himself was a larger-than-life figure in France—charming, controversial, and closely connected to the royal court, including Queen Marie Antoinette. According to his now-translated memoir, during a visit to Washington at his New Windsor headquarters, the Duke nearly drowned while crossing the icy Hudson River. His boat capsized, and he had to scramble over floating ice to reach the shore. After reading his letters and personal accounts, I knew this was a story that needed to be told—the story of how a French aristocrat, soldier, and adventurer became part of the American Revolution and George Washington's friend. As with all my history books, I rely exclusively on primary source documents, many of which are newly discovered. I include many of these documents verbatim, allowing readers to experience their original tone and style. I never alter the content of a primary source or impose bias; instead, I provide narration to explain the context and environment of the events. Reading this book offers an authentic sense of what life was like during this period of the American Revolutionary War.