The invasion of the Iberian Peninsula in 1807-08 by Napoleon Bonaparte's forces proved to be critical for the independence struggle in South America, during which the local elites of Upper Peru remained mostly loyal to Spain, supporting Junta Central, a government which ruled in the name of the overthrown king Ferdinand VII of Spain. A number of radical criollos in 1808-10 began a local power struggle. Pedro Domingo Murillo proclaimed an independent state in Upper Peru in the name of king Ferdinand VII. During the following seven years Upper Peru became the battleground between the armed forces of independent United Provinces of the Rio de la Plata and royalist troops from Viceroyalty of Peru.