Spain's Progressive Biennium and Liberal Union Era (1854-1868)

Since 1850, the authoritarianism and corruption of moderate governments intensified. This was compounded by Carlist opposition. Democrats, who had made their appearance in the uprisings of 1848 in some Spanish cities, demanded universal suffrage.

The Progressive Biennium (1854-1856)

The most significant revolution of 1854 was organized by moderate leftists and carried out with the pronouncement of General O'Donnell to overthrow the government. After an initial difficult time following a clash with government troops, O'Donnell managed to attract the support of broad popular strata, progressives, and Democrats with the publication of the Manifesto of Manzanares. The manifesto demanded reform of electoral and printing laws, decentralization of state power, and the restoration of the national militia. The proclamation spread through major cities, where revolutionary committees were formed. One of the most important events took place in Madrid, followed by several days of insurrection and barricades.

After these events, Queen Isabella II instructed General Espartero, who had not directly participated in the revolution, to form a new government at the head of the progressives.

Instability and Reforms During the Biennium

The two years of this period were highly unstable. The most significant reforms of the period were:

• The Desamortización de Madoz (Madoz Confiscation), supplementing the one carried out by Mendizábal. It was the largest confiscation in terms of sales volume and marked the final demise of amortized (dead hand) goods. It neither solved the chronic problem of public debt nor did it benefit the less wealthy, who were most affected, as they subsequently lost access to communal lands. The scale of these confiscations was extraordinary.
• Restoration of laws and institutions from the 1830s.
• Adoption of new Railway, Companies, and Credit Bank Acts.
• Drafting of a constitution in 1856, which was never enacted.

During the biennium, Spain witnessed serious social unrest and subsistence riots. These two years culminated in Espartero's dismissal and O'Donnell's appointment.

The Governments of the Moderate and Liberal Union (1856-1868)

In the years following the end of the biennium, there were several progressive and moderate governments, and the Unión Liberal (Liberal Union) entered the political scene. This was a new party created and led by O'Donnell, aiming to be a centrist group uniting moderate leftists and progressives. This new force advocated for moderate constitutionalism, expanded press freedom, and promoted economic development.