The Anglo-Spanish War was a conflict between the English Protectorate under Oliver Cromwell, and Spain, between 1654 and 1660. It was caused by commercial rivalry. Each side attacked the other's commercial and colonial interests in various ways such as privateering and naval expeditions. In 1655, an English amphibious expedition invaded Spanish territory in the Caribbean. In 1657, England formed an alliance with France, merging the Anglo–Spanish war with the larger Franco-Spanish War resulting in major land actions that took place in the Spanish Netherlands.

Portsmouth is a port city and unitary authority in Hampshire, England. Most of Portsmouth is located on Portsea Island, off the south coast of England in the Solent. This means Portsmouth is the only English city not located primarily on the mainland. Located 74 miles (119 km) south-west of London, 50 miles (80 km) west of Brighton and Hove, and 22 miles (35 km) south-east of Southampton; Portsmouth is part of the South Hampshire conurbation. It is the most densely populated city in the United Kingdom, with a population last recorded at 208,100.