English victory over a Franco-Castilian-Flemish fleet in the Battle of Margate off the coast of Margate.

The Kingdom of England was a sovereign state on the island of Great Britain from the 10th century, when it was unified from various Anglo-Saxon kingdoms, until 1 May 1707, when it united with Scotland to form the Kingdom of Great Britain, which would later become the United Kingdom. The Kingdom of England was among the most powerful states in Europe during the medieval and early modern periods.

The Kingdom of France is the historiographical name or umbrella term given to various political entities of France in the medieval and early modern period. It was one of the most powerful states in Europe from the High Middle Ages to 1848 during its dissolution. It was also an early colonial power, with colonies in Asia and Africa, and the largest being New France in North America geographically centred on the Great Lakes.

The Crown of Castile was a medieval polity in the Iberian Peninsula that formed in 1230 as a result of the third and definitive union of the crowns and, some decades later, the parliaments of the kingdoms of Castile and León upon the accession of the then Castilian king, Ferdinand III, to the vacant Leonese throne. It continued to exist as a separate entity after the personal union in 1469 of the crowns of Castile and Aragon with the marriage of the Catholic Monarchs up to the promulgation of the Nueva Planta decrees by Philip V in 1716.

The County of Flanders was one of the most powerful political entities in the medieval Low Countries, located on the North Sea coast of modern-day Belgium and north-eastern France. Unlike the neighbouring states of Brabant and Hainaut, it was within the territory of the Kingdom of France. The counts of Flanders held the most northerly part of the kingdom, and were among the original twelve peers of France. For centuries, the economic activity of the Flemish cities, such as Ghent, Bruges and Ypres, made Flanders one of the most affluent regions in Europe, and also gave them strong international connections to trading partners.