In 1791 Morillo enlisted in the Real Cuerpo de Marina (Spanish Royal Marine Corps) and participated in the Battle of Trafalgar in which he was wounded and made prisoner by the English in 1805. He also fought against Napoleon Bonaparte in 1808 during the Peninsular War (part of Napoleonic Wars) to defend his mother country Spain against the French invasion. Once the war ended and the Spanish monarchy was restored, King Ferdinand VII of Spain appointed him Expedition Commander and General Captain of the Provinces of Venezuela on 14 August 1814. He set sail with a fleet of 18 warships and 42 cargo ships and disembarked in Carupano and Isla Margarita with the mission to pacify the revolts against the Spanish monarchy in the American colonies. He travelled to La Guaira, Caracas, Puerto Cabello, Santa Marta and Cartagena de Indias (United Provinces of New Granada) in a military campaign to fight Simon Bolívar's revolutionary armies.