The Coup of 1856 in Luxembourg was a crucial turning point for the Grand Duchy, as it established a precedent for unilateral governmental decision-making. Prompted by increasing social and political tensions, the coup was largely orchestrated by elements within the government who favored a strong, centralized authority over a more liberal, parliamentary approach. On November 27, 1856, Grand Duke Henri, acting on the advice of his supporters, officially adopted a new constitution that reflected these reactionary ideals. This constitution limited civil liberties and curtailed the powers of the existing parliamentary system, which had been growing increasingly popular among the populace. The move was aimed at consolidating power firmly in the hands of the Grand Duke, ostensibly to restore order during a time of upheaval.

The reactionary constitution abolished several reforms that had been put into place during previous liberal governments and sought to reinforce a more conservative governance structure. The decision did not occur in isolation but was set against the backdrop of broader European trends, where many nations were grappling with similar conflicts between liberal ideals and conservative traditions. The response among the citizens varied, with some supporting the Grand Duke's measures as necessary for stability, while others decried it as a blatant disregard for democratic principles.

In the aftermath of the coup and the new constitution, Luxembourg experienced a period of political repression, with dissidents facing increased scrutiny and the government imposing restrictions on free speech and political assembly. Although the Grand Duke aimed to restore order, the adoption of the reactionary constitution ultimately led to residual discontent within segments of the society. This period marked a regressive step in Luxembourg's development towards a more democratic form of governance, which would not return to the fore until the late 19th century.