1. In the early 19th century, Napoleon invaded Spain and Portugal, sparking the Spanish War of Independence. This war lasted from 1808 to 1814, ending with the French defeat and Ferdinand VII's return to the Spanish throne.
2. Ferdinand VII abolished the liberal Constitution of 1812 and established an absolute monarchy, causing political disorder. Most Spanish colonies gained independence during this time.
3. Isabella II became queen in 1833 but revolutions and unrest led to her exile in 1868, beginning a period of instability with multiple short-lived governments over the next decade.