The Spanish liberal revolution was a long process that spanned until 1840, including two long wars (the War of Independence in 1808-1814 and the Carlist War in 1833-1839), and an alternation of constitutional attempts (the Courts of Cadiz in 1810, the Constitutional Triennium in 1820-1823) with counterrevolutionary experiences: the restoration of Fernando VII in 1814, the end of the constitutional regime in 1823 -following the incursion of a French army of 65.000 men-, the absolutist decade in 1823-1833, and the Carlist insurrection in 1833. In the Basque Country this process had its own specific manifestations.
Between 1808 and 1840 -a period in which Spain also lost all of its empire- the war of independence, the loss of America, the misgovernment of Fernando VII, and the Carlist war basically prevented Spain from having a proper State. Between 1803 and 1840 the country suffered a real administrative chaos. And precisely due to this, the largest problem of Spain in the 19th century, and part of the 20th century, was to articulate the country in way that it would become a real national State. The problem for the Basque Country (and Navarra) in this famework was to see if the national Constitution and the regional Fueros (i.e, the constitutional unity and the foral regional regimes) were compatible or not.
Carlism and the Carlist wars were of great importance for the Basque Country, although the later were not "national" Basque wars as the posterior nationalism has tried to make believe. These were, without doubt, historical happenings of great complexity. Carlism -which the liberal propaganda denounced as a legitimist and ultra-catholic uprising supported by the Church and with strong rural roots- was a political and social movement with a traditionalist and anti-liberal ideology, in defense of the traditional and Catholic Monarchy, and supported not only by the rural world and the clergy, but also by nobility groups and medium artisanal classes from semi-urban or semi-rural cities and towns. The two Carlist wars (1833-1839 and 1872-1876) finished with the victory of the liberal armies, and became key events for the establishment of liberalism in Spain. The wars produced thousands of deaths and meant the end of the Basque foral regime. Initially it was heavily modified, but later due to a law of July 21st 1876 the foral regime was completely abolished. Liberals may have won the wars, but Carlism and the Fueros capitalized all the legends, memories and myths. The Carlist wars fixed the Basque stereotype of ancient and noble people, settled in the mountains, proud of their ancient traditions and language, as well as tenacious fighters for their Fueros and freedom.
Carlism was a Spanish and Catholic movement: even the Basque Carlism agreed to a Basque-Navarran personality that was an essential part of the traditional Catholic concept of Spain. Following the first Carlist war, Fuerism, which strictly speaking was fostered by the moderate liberal Basques and Navarrans -and not by Carlism-, came to be a sort of political "constitution" of the Basque and Navarra provinces in the 19th century that did not argue with the unity of Spain. As a matter of fact it was the other way around, the Fueros were presented from their perspective as the big contribution of the Basque people to the history of Spain.