The St. James' Day Battle was a naval battle of the Second Anglo-Dutch War which was fought off the coast of Kent on 25 July 1666.
A month after the Four Days' Battle, the Dutch fleet of 88 ships, under Michiel de Ruyter, discovered the refitted English fleet of 89 ships sailing north near the North Foreland of Kent. The Dutch pursued the English fleet, resulting in a battle being fought on 25 July. The wind split the Dutch fleet in half, enabling Thomas Allin's English van to engage Johan Evertsen's Dutch van. The outnumbered Dutch van was mauled, and Evertsen, Vice-Admiral Rudolf Coenders, and Lieutenant-Admiral Tjerk Hiddes de Vries was mortally wounded. Lieutenant-Admiral Cornelis Tromp rescued De Ruyter from the English rear, causing its vice commander Edward Spragge to swear vengeance. On the second day of battle, Tromp broke off the pursuit of the English rear, and he failed to rejoin the main battle, causing De Ruyter to seek death from an enemy cannonball, to no avail. The wind saved the Dutch fleet by turning them west, allowing them to reach the safety of the Flemish shoals.
The Dutch defeat at the St. James' Day Battle, and the allegations of negligence against the Orangist Tromp, led to political chaos in Holland as Tromp's brother-in-law Johan Kievit launched a failed Orangist coup, and Tromp was forbidden to serve in the fleet (leading to a failed attempt on De Ruyter's life in 1669). However, London had been devastated by the Great Plague and the Great Fire at the same time as King Charles II of England used up the last of his financial reserves for the St. James' Day Battle.