The Secret Treaty of Dover was a significant agreement between Charles II of England and Louis XIV of France, finalized in Dover, England. The backdrop of the treaty was the increasing rivalry between England and the Dutch Republic. Both monarchs recognized the potential advantages of collaborating against a common enemy. The treaty not only laid plans for military action but included a personal commitment from Charles II to convert to Catholicism, reflecting the religious tensions influencing European politics of the time.

The agreement outlined military collaboration, with France pledging to support England's military efforts against the Dutch Republic. In exchange, Charles II would receive financial backing from France, thus ensuring that England would engage actively in the Third Anglo-Dutch War. The treaty's secretive nature underscored the clandestine diplomacy prevalent in 17th-century Europe, where alliances were often formed in the shadows.

The implications of the treaty were far-reaching, leading to aggressive actions against the Dutch and exacerbating tensions within both nations. The subsequent war would not only strain England's resources but also alter the balance of power in Europe, underscoring the interconnectedness of European politics during this era.