The British invasions of the Río de la Plata were a series of unsuccessful British attempts to seize control of the Spanish colonies located around the La Plata Basin in South America (today part of Argentina and Uruguay). The invasions took place between 1806 and 1807, as part of the Napoleonic Wars, when Spain was an ally of France.

The invasions occurred in two phases. A detachment from the British army occupied Buenos Aires for 46 days in 1806 before being expelled. In 1807, a second force occupied Montevideo, remaining for several months, and a third force made a second attempt to take Buenos Aires. After several days of street-fighting against the local militia and Spanish colonial army, in which half of the British forces were killed or wounded, the British were forced to withdraw.

The social effects of the invasions are among the causes of the May Revolution. The criollos, who had so far been denied important positions, could get political strength in military roles. The successful resistance with little help from the peninsula fostered the desire of self-determination. An open cabildo and the Royal Audience of Buenos Aires deposed the viceroy Rafael de Sobremonte and designated instead the popular hero Santiago de Liniers, which was a complete unprecedented action: before that, the viceroy was only subject of the King of Spain himself, and no Spanish American had authority over him.