May Revolution
The mutiny of Aranjuez in 1808 led King Charles IV of Spain to abdicate in favor of his son, Ferdinand VII. Charles IV requested that Napoleon restore him to the throne; instead, Napoleon crowned his own brother, Joseph Bonaparte, as the new Spanish King. These events are known as the Abdications of Bayonne. Joseph's coronation was met with severe resistance in Spain, which started the Peninsular War, and the Supreme Central Junta took power in the name of the absent king. This also led to Spain switching allegiances from France to Britain. France eventually invaded Sevilla, and a Council of Regency based in Cadiz replaced the disbanded Supreme Central Junta.
May Revolution
The change was potentially favorable for Britain, as trade with the cities of the area was facilitated, without the monopoly that Spain had maintained over their colonies for centuries. However, Britain's first priority was the war against France in Europe, and they could not appear to support American independence movements or allow the military attention of Spain to be divided onto two different fronts. Consequently, they pushed to avoid explicit independence demonstrations. This pressure was exerted by Lord Strangford, the British ambassador at the court of Rio de Janeiro; he expressed support for the Junta, but under the condition that "...the behavior is consistent, and that [the] Capital [is] retained on behalf of Mr. Dn. Ferdinand VII and his legitimate successors". Later conflicts between Buenos Aires, Montevideo and Artigas led to internal conflicts on the British front, between Strangford and the Portuguese regent John VI of Portugal.