The First Carlist War (1833-1839) was a civil conflict in Spain that arose after the death of King Ferdinand VII. The war was fought between supporters of his daughter, Isabella II, who represented the liberal faction, and those who backed her uncle, Carlos María Isidro, who led the conservative faction known as the Carlists. The Carlists sought to uphold traditional monarchy and regional rights, particularly in Catalonia and Navarre. The conflict was marked by guerrilla warfare and significant battles, such as the Battle of Luchana and the Siege of Bilbao. Ultimately, the war ended with the defeat of the Carlists and the consolidation of Isabella II's rule, leading to a period of political instability in Spain that would continue for decades.