The March Revolution of 1848 in Denmark was a pivotal series of events that led to the establishment of a constitutional monarchy and the adoption of the Danish Constitution. This revolution took place against a broader backdrop of upheavals across Europe, as the February and March Revolutions that year swept through several countries, including France and Germany, sparking widespread demands for democratic reforms.
King Frederick VII ascended to the Danish throne on January 20, 1848, at the age of 39. He was known for his lack of engagement with state affairs and was willing to consider the idea of a constitutional state, unlike his predecessors who had ruled as absolute monarchs. Shortly after his coronation, he maintained the previous ministers and made two new appointments to the Council of State. Around this time, the draft constitution developed under his father, Christian VIII, was moving forward. On January 28, 1848, the Danish government announced plans for a joint constitutional framework for the entire Kingdom of Denmark, which included both the Kingdom itself and the Duchies of Schleswig and Holstein. This arrangement proposed equal representation between Denmark proper, with its population of 1.3 million, and the Duchies, which had 800,000 inhabitants.
The National Liberal Party, advocating for a constitution focused on Denmark up to the Eider River, was dissatisfied with this proposal, viewing it as a violation of Danish rights. At the same time, the people in the Duchies opposed any joint constitution with Denmark, as they sought more independence.
On March 20, 1848, news reached Copenhagen that representatives from Schleswig and Holstein had met in Rendsburg, demanding a free constitution, the unification of Schleswig and Holstein, and Schleswig's entry into the German Confederation. Reacting to this, National Liberal leader Orla Lehmann declared that the Duchies were in open rebellion. He and other party leaders called for a public meeting at the Casino Theatre that evening to discuss the situation, while another meeting of the Borgerrepræsentation (People's Representation) was convened to draft a declaration to the king demanding political reforms.
The meeting at the Casino Theatre drew 2,500–3,000 participants. Hvidt and Lehmann, who arrived late due to their earlier meeting with the Borgerrepræsentation, presented the declaration, which demanded that the king replace his ministers and establish a new government. It was agreed that the next day, the crowd would march to the royal palace, Christiansborg, to present their demands.
On March 21, between 15,000 to 20,000 people gathered at Gammeltorv, the main square in Copenhagen, and marched to Christiansborg. However, upon their arrival, they learned that earlier that morning, King Frederick VII had already dismissed his ministers at the urging of his advisor Bardenfleth, who sought to prevent Schleswig from uniting with the German Confederation.
Over the following days, efforts to form a new government continued. Several attempts failed, but on March 22, former finance minister Adam Wilhelm Moltke successfully established a coalition government known as the Moltke I Cabinet or the March Ministry. This new government, which included opposition figures such as Ditlev Gothard Monrad, Tscherning, Hvidt, and Lehmann, marked the beginning of Denmark's transition to a constitutional monarchy. Although the National Liberals were initially dissatisfied, they accepted the government based on King Frederick VII’s promise to assume the role of a constitutional monarch and delegate responsibility to his ministers.
The new government responded to the demands from the Duchies on March 24, rejecting Schleswig's entry into the German Confederation but granting it increased provincial independence and declaring it would have a joint constitution with Denmark. Holstein was to have a separate constitution as a German Confederate state. Before these plans could reach the Duchies, an open rebellion erupted in Holstein on March 23, escalating into the Three Years' War (First Schleswig War) from 1848 to 1850, as the conflict over Schleswig and Holstein's status became a broader struggle between Danish and German interests.