Hoping to extend the Continental System, Napoleon invaded Iberia and declared his brother Joseph the King of Spain in 1808. The Spanish and the Portuguese revolted with British support. The Peninsular War lasted six years, noted for its brutal guerrilla warfare, and culminated in an Allied victory. Fighting also erupted in Central Europe, as the Austrians launched another attack against the French in 1809. Napoleon defeated them at the Battle of Wagram, dissolving the Fifth Coalition formed against France. By 1811, Napoleon ruled over 70 million people across an empire that had domination in Europe, which had not witnessed this level of political consolidation since the days of the Roman Empire. He maintained his strategic status through a series of alliances and family appointments. He created a new aristocracy in France while allowing the return of nobles who had been forced into exile by the Revolution.

Answer this question, if possible (if impossible, reply "unanswerable"): Who did Napoleon declare King of Spain in 1808?
his brother Joseph