Anglo-French War (1778–1783)

10 July 1778: a letter to the Admiral of France

On 10 July 1778, Louis XVI issued a letter authorizing open maritime reprisals against Britain. The surviving instrument is an operational order rather than a conventionally styled formal declaration of war.

Louis ordered French naval commanders to attack, capture or destroy vessels belonging to the British king and to seize British merchant shipping. He directed the Admiral of France, the Duke of Penthièvre, to issue privateering commissions to qualified French subjects who could arm sufficiently strong vessels.

The naval minister Antoine de Sartine countersigned the letter beneath the king's signature.

The grievances the order named

The order cited the attack on the frigate Belle Poule, whose 17 June engagement with HMS Arethusa was presented as an insult to the French flag.

It also cited the seizure of three further French vessels — the frigates Licorne and Pallas and the lugger Coureur — together with attacks on French commerce and alleged British treaty violations.

Whether it counts as a declaration

The date of the letter is securely documented; its description as a declaration of war is not. Contemporary American diplomats reported that the Anglo-French war remained formally undeclared, while later histories often treat the 10 July order as France's declaration or first official act of war.

Because neither government wanted to appear the aggressor, "declaration of war" is a convenient modern label rather than a precise description of the surviving French document.

Seventeen days after the order, on 27 July, the principal fleets fought off Ushant.