The First Cevallos expedition was a series of Spanish military operations in South America during the Fantastic War. Under the command of the governor of Buenos Aires, Pedro Antonio de Cevallos, the expedition captured the Portuguese settlement of Colónia do Sacramento and fought off a joint Anglo-Portuguese attempt to recapture it. All military activities in the region concluded with the 1763 Treaty of Paris.

Colonia del Sacramento is a city in southwestern Uruguay, by the Río de la Plata, facing Buenos Aires, Argentina. It is one of the oldest towns in Uruguay and the capital of the Colonia Department. It has a population of around 27,000.