On this day in 1778, the United States and France signed two treaties – the Treaty of Alliance and the Treaty of Amity and Commerce – that established strong and perpetual military, economic, and political ties. As the Revolutionary War grinded on, the Patriots realized that they needed diplomatic and military support from abroad to succeed. France was the natural choice, as it was a longstanding rival to Great Britain and the only country that rival its power.

To that end, the French proved to be the deciding factor in America’s victory: almost immediately after the pacts were signed, they provided financial and material support to the war effort, and committed themselves to supporting the U.S. until it attained full independence. Their contributions included over a billion dollars, the majority of gunpowder for the Continental Army, naval support (as the U.S. lacked a full-fledged navy), uniforms and supplies, military training and leadership, and nearly 45,000 personnel. Almost as many French fought in the decisive Battle of Yorktown, which helped end the war, as Americans did.

Indeed, France wracked up so much debt in funding the U.S. war effort (in addition to what was owed from previous wars with the British), that it suffered political and economic problems that culminated in the French Revolution.

Pictured above is a depiction of the signing of the two treaties by Charles E. Mills, courtesy of the Library of Congress.