1678

1678 (MDCLXXVIII) was a common year in the Gregorian calendar. The most significant events of the year occurred in Europe, where it marked the beginning of a comprehensive peace process that reshaped the continent's political map.

The Peace of Nijmegen was concluded in 1678 and 1679, a set of treaties involving France, the Dutch Republic, Spain, and the Holy Roman Empire, that ended the Franco-Dutch War and related hostilities. The agreements redefined borders and power relations, confirming France as a major European power and weakening Spanish influence in the Low Countries, while the Dutch Republic retained its position as a key maritime and commercial power.

In Britain, 1678 is notable for the exposure of the Popish Plot, a false accusation propagated by Titus Oates that Catholics planned to assassinate Charles II. The episode intensified anti-Catholic sentiment, fueling the political movement that led to the Exclusion Crisis, which sought to prevent James, Duke of York, from succeeding to the throne.

Elsewhere, the year formed part of a broader pattern of imperial competition in the late 17th century, with European powers contesting colonial and strategic interests in North America and elsewhere. The year did not see a single defining territorial change outside these larger wars, but it contributed to the reshaping of the European balance of power that would influence events in the following decades.