During Early Modern Times, the Netherlands changed sovereignty according to dynastic and political hazards. Following the death of Charles the Bold, Duke of Burgundy (1477), the Netherlands passed to the Habsbourgs. During the 16th and 17th centuries, the Duchy of Luxembourg, along with the other provinces that made up the territory of the Netherlands, belonged to the Spanish Habsbourgs.
Luxembourg occupied an important strategic position on the European chessboard. From the 16th century onwards, the country was drawn into the numerous wars fought for the hegemony in Europe by the Spanish Habsburgs and the Valois, and finally the Bourbons of France. Luxembourg City was progressively transformed into one of the most renowned fortresses of Europe, a true 'Gibraltar of the North'.
In 1659, the Treaty of the Pyrenees, which put a provisional end to the Franco-Spanish conflict, dismembered the entire southern part of the Duchy to the advantage of France. In 1684, the fortress of Luxembourg was besieged by the armies of Louis XIV. After capturing the city, the French engineer Vauban, who led the siege operations, carried out extensive fortification works. During a short period, from 1684 to 1697, the Duchy of Luxembourg remained under French rule. In 1715, following the War of the Spanish Succession, the southern Netherlands passed to the Austrian branch of the Habsburgs.
In contrast to the two preceding centuries, the 18th century was marked by a period of peace in Luxembourg. The reigns of Charles VI (1715-1740), Maria Theresa (1740-1780) and Joseph II (1780-1790) brought about a revival in several areas. The Austrian reforms, such as the Theresian Land Register introducing fiscal equality and the Edict of Toleration granting non-Catholics the freedom of religion, already signaled the innovations of the French Revolution.
In 1795, the French revolutionary troops conquered the fortress and Luxembourg was annexed to France as the 'Département des Forêts' (Forests Department). The introduction of conscription, a system of compulsory military recruitment, triggered a peasant uprising in 1798, known as the 'Klëppelkrich' (Cudgel War). Under Napoleon, the more moderate French regime gained more widespread acceptance among the population.