First Treaty of London

The First Treaty of London, also known as the Treaty of Windsor, was formally agreed on 8 May 1358 at Windsor Castle in England. Its terms ended the then 21-year-old Anglo-French conflict now known as the Hundred Years' War. It was sealed by Edward III, king of England, and John II, king of France; the latter was a prisoner in England, having been captured with much of his council at the Battle of Poitiers in 1356.

The treaty set John's ransom at four million écus. This was £667,000 – the equivalent of the peacetime income of the English Crown for about 20 years. In exchange for peace, France was to transfer to England approximately a quarter of its territory; Edward would give up his claim to the French throne. The first instalment of the ransom – 600,000 écus (£100,000) – was due to be paid on 1 November, but with the French government collapsing into insurrection and anarchy it proved impossible to raise. Edward refused to accept less than full performance of the terms of the treaty and it lapsed. Subsequent negotiations led to the Second Treaty of London in March 1359 but its terms were so harsh that the French government repudiated it. Hostilities resumed in October, when Edward again invaded France.