Excerpts from Books and Wikipedia
"The Battle of the Dunes, fought on 14 June (Gregorian calendar), 1658, is also known as the Battle of Dunkirk. It was a victory of the French army and their Commonwealth of England allies, under Turenne, one of the great generals of his age, over the Spanish army and their English Royalist and French Fronde rebels, led by John of Austria the Younger and Louis II de Condé. It was part of the Franco-Spanish War and the concurrent Anglo-Spanish War, and was fought near Dunkirk (Dutch for 'Church in the dunes') a fortified port city on the coast of the English Channel in what was then the Southern Netherlands that belonged to Habsburg Spain. The French army had laid siege to Dunkirk and the Spanish army was attempting to raise the siege. . . . Cromwell died two months after the battle and was succeeded by his son's protectorship, which ended nine months later, and the Commonwealth fell into confusion, whereupon Charles II returned to the throne in May 1660. Charles would sell Dunkirk back to the French in 1662 for £320,000." [Wikipedia]