Calais was a strategically important port city in northern France that had been under English control since 1347. It was the last remaining English possession on the continent, and its loss was a significant blow to English prestige.
Mary I, also known as "Bloody Mary", lost Calais to France in 1558, during her reign. The loss of Calais was a major setback for England, and it marked the end of English ambitions to hold territory in France.