Who was Isabella II?
Isabella II was Queen of Spain from 1833 to 1868, when she was deposed. At the time she acceded to the throne, the old Salic law was still thought by many in Spain to be the best way to determine the royal succession. The Salic law was an ancient law code that, among other things, established that royal thrones should only descend through the male line. But Isabella's father, King Ferdinand VII, set aside the Salic law in order to allow his daughter to succeed him to the Spanish throne.
Not surprisingly, Ferdinand's actions proved immensely controversial, and many Spanish nobles flatly refused to accept a female monarch. Ferdinand's brother, Carlos, led a revolt against the changed succession, as he would have been entitled to the throne under the old Salic law. His followers were known as Carlists, and their challenge to the state's authority constituted a destabilizing force in Spanish politics and society for a number of years.
Despite the Carlists' best efforts, Isabella came to the throne as her father had intended. However, her reign proved to be an unhappy one, constantly undermined as it was by various plots, conspiracies, and seemingly endless palace intrigue. As so much of the Spanish nobility was against her, Isabella came dangerously over-reliant on the military to keep her in power. Isabella made life much harder for herself by constantly interfering in politics, despite the fact that Spain was by then a constitutional monarchy, with royal power kept within strict bounds.
Under Isabella, Spain became embroiled in a series of largely pointless overseas conflicts and encountered growing resistance from its colonial subjects. Also, Isabella's open preference for reactionary elements in society put her at odds with a growing desire for change. There was a sense of inevitability, then, when a revolt by some of her generals led to her being deposed. If Isabella could no longer count on the loyalty of her own troops, then her power base was effectively gone. The First Spanish Republic was born, thus ending Isabella's brief and largely unsuccessful reign.
Isabella went into exile in France, where she saw out the rest of her days. However, six years after she was deposed the Republic collapsed and Isabella formally abdicated in favor of her son, Alfonso XII, who returned to Spain as king.