Complex sentence: Spain, which had a garrison at Puerto Soledad on East Falkands, ruled the islands from Montevideo until 1811 when it withdrew due to the military pressures created by the Peninsular War in Spain and the growing calls for independence by its colonies in South America.
Split into simpler sentences: Spain, which had a garrison at Puerto Soledad on East Falkands, ruled the islands from Montevideo until 1811 when it was forced to withdraw. This was due to the military pressures created by the Peninsular War in Spain and the growing calls for independence by its colonies in South America.