Final answer:
When Napoleon invaded Portugal in 1807, the Portuguese Crown, led by Prince Regent João, relocated to Brazil under British protection and maintained their alliance with Britain. This move contributed to the establishment of the Kingdom of Brazil and eventually to Brazilian independence.
Step-by-step explanation:
How the Portuguese Crown Reacted to Napoleon's Invasion
When Napoleon invaded Portugal in 1807, the Portuguese Crown faced a difficult situation. Queen Maria, although she wore the Portuguese Crown, had been declared mentally incapacitated, so her son, the Prince Regent João, had to decide the nation's fate. Under the threat of French forces arriving in Lisbon and after consultation with Britain's Lord Strangford, João decided to move the court to Brazil, where he ruled in exile until 1821. This move also entailed a close economic relationship with Britain, as the British received generous commercial privileges in Brazil for facilitating the transportation of the Portuguese royal family and court.
During the Napoleonic Era, Spain and Portugal took different sides, with Spain becoming a French satellite and Portugal maintaining its alliance with Britain. Portugal's act of defiance against Napoleon's Continental System led to an invasion of the Iberian Peninsula. As French troops commanded by General Junot advanced, the strategic relocation of the Portuguese court marked a significant historical shift, resulting in the establishment of the Kingdom of Brazil in 1815 and further political consequences, including Brazilian independence under Pedro I after João VI's return to Europe.