May 17, 1756

Seven Years' War

George II declares war on France

The declaration effectively conceded the war was already two years old: its own text calls the seizure of an Ohio fort in 1754 a commencement of war.

17 May 1756: one folio page, issued at Kensington

At Kensington on 17 May 1756, King George II issued a formal declaration of war against the French king. It was printed as a single folio broadside.

The text cited French actions in North America and the West Indies, earlier seizures and fighting at sea, and — most immediately — the French invasion of British-held Minorca.

What it ordered

George II directed British military and naval officers to carry out acts of hostility against the French king and his subjects, and forbade British subjects to correspond or communicate with them.

Ships carrying soldiers, arms, ammunition or other contraband to French territories became liable to capture as lawful prizes. French subjects in Britain who behaved dutifully were promised safety.

Not the day the fighting started

Anglo-French hostilities had been running in North America since 1754, and the declaration's own text described the seizure of an Ohio fort that year as a commencement of war. Cambridge's account dates the European war's beginning elsewhere again — to Frederick II's invasion of Saxony on 29 August 1756.

The proclamation was printed in the London Gazette on 18 May, which is why many accounts carry that date instead. France issued its own declaration against Britain on 9 June.

Sources

Researched 23 Aug 2026 6 sources 2 audit passes

How this was checked

Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →

What the sources leave uncertain

The document itself is unequivocally dated 17 May at Kensington. The frequent date 18 May reflects its publication in the London Gazette, not the date written on the declaration.
Calling this the day the entire Seven Years’ War ‘formally began’ is historiographically misleading. Anglo-French hostilities had begun in North America in 1754, while Cambridge’s account dates the European war’s beginning to Frederick II’s invasion of Saxony on 29 August 1756.