In the history of Spain, the bienio progresista (Spanish pronunciation: [ˈbjenjo pɾoɣɾeˈsista], "Progressive Biennium" or "Progressivist Biennium") was the two-year period from July 1854 to July 1856, during which the Progressive Party attempted to reform the political system of the reign of Isabella II, which had been dominated by the Moderate Party since 1843 in the so-called década moderada.
Furthermore, all but the wealthiest were disenfranchised by a system of census suffrage that left less than one percent of the population eligible to participate in the country's electoral politics.
For the most part, this meant the Progressives, but there were also moderates such as General Leopoldo O'Donnell who were simply opposed to what an increasingly corrupt and ineffective regime.
The dismissal of prime minister Juan Bravo Murillo toward the end of 1852 marked the acceleration of the decline of the Moderate regime.
On 28 June 1854, O'Donnell, who had been hiding in Madrid during a wave of persecutions of prominent figures not aligned with the current regime, managed to unite diverse forces and to confront troops loyal to the government at Vicálvaro southeast of Madrid, where he demanded a new government that would put an end to the corruption.
The organs of government that ought to be constituted in free provinces, the Cortes generales that will later bring them together, the Nation itself, finally, will set the definitive bases for the liberal regeneration to which we aspire.
On 17 July, civilians and soldiers took to the streets of Madrid, (as well as Alzira, Cuenca, Logroño, Valencia and Zaragoza) in a violent uprising that threatened the life of queen mother Maria Christina, who had to seek refuge.
Second, another law gave major benefits and privileges to whoever would invest in the construction of railways, given that transport was essential to the process of industrialization that was beginning to develop in Spain.
Third and finally, a liberalization of banking and corporate law attempted to expand the financial system to underwrite industrial development.