First Cevallos expedition The First Cevallos expedition was a military action between September 1762 and April 1763 , by the Spanish forces led by Don Pedro Antonio de Cevallos , Governor of Buenos Aires , against the Portuguese in the Banda Oriental as part of the Seven Years ' War . The Portuguese territories of Colonia del Sacramento were conquered by the Spaniards and the Anglo - Portuguese forces were defeated and forced to surrender and retreat . The Colonia of Sacramento and the near territories were under Spanish control until the Treaty of Paris ( 1763 ) . Prelude . In January 1762 , Spain joined France against Great Britain in the Seven Years ' War , in accordance with the Third Pacte de Famille . The plan was to attack Portugal , which had been neutral up to then , but which was an important economical ally of Great Britain . On May 9 Spain invaded Portugal , and also decided to attack Portugal in South America , and in particular to take the long disputed Colonia del Sacramento . The expedition in 1762 . In the first days of January 1762 the frigate " Victoria " commanded by Carlos José de Sarriá , sailed from Cadiz to Buenos Aires with orders for the Governor of Buenos Aires , Pedro Antonio de Cevallos , to attack and take Sacramento . He started preparations and in September 1762 he had assembled enough men and ships to launch an attack . The fleet sailed across the Rio de la Plata , and disembarked on September 14 . The army was joined by a force of 1200 Indians on October 1 . The siege of the city started on October 5 . The relations between Cevallos , who commanded the army , and Sarria , who commanded the fleet , were very bad . After disembarking the army and without approval of Cevallos , Sarria sailed his fleet of 16 ships back to Buenos Aires . Luckily for the Spanish , the Portuguese were ill prepared and on October 31 , 1762 Vicente da Silva , the governor of the city , capitulated . The sinking of the Lord Clive . Great Britain , which was now officially at war with Spain , did not participate in these battles , but the East India Company had plans to conquer Spanish territory in South America and bought two old warships from the Admiralty . The biggest ship was HMS Kingston ( 1697 ) which was renamed " Lord Clive " ( 60 ) , the other ship was the " Ambuscade " ( 40 ) . The small squadron , under the command of Robert McNamara left Lisbon on August 30 and was joined in Rio de Janeiro by two Portuguese warships ( among which was the frigate " Glória " ( 38 ) transporting 500 foot soldiers , and five storeships . On November 2 , the squadron sailed from Rio de Janeiro towards the mouth of the Río de la Plata to attack Buenos Aires and Montevideo , but soon abandoned the project because Spanish defenders on both cities were fully alerted and well prepared . On January 6 , 1763 , McNamara decided to attack and retake Colonia do Sacramento also in Spanish hands . 60 - gun " Lord Clive " and the 40 - gun HMS " Ambuscade " along with 38 - gun Portuguese " Gloria " anchored near the city and started bombardment , but they received unexpected strong resistance from the city gun battery . After three hours of fire exchange , a fire erupted on the " Lord Clive " , it quickly extended and ship ' s santabarbara blew up , it sunk immediately . There were 272 fatalities on board , including the expedition ' s commander Captain Robert McNamara . HMS " Ambuscade " and " Gloria " were badly damaged too , and retired from combat . The expedition in 1763 . Still in control of Sacramento , Cevallos marched his army in the spring of 1763 to the east and took on April 19 the " Santa Teresa fortress " , near the present - day city of Chuy on the Uruguay - Brazilian border , and " Santa Tecla " and " San Miguel " a few days later . On April 24 he arrived at Rio Grande de São Pedro only to learn that peace had been signed and that the war was over . Aftermath . Sacramento and all the territory conquered by the first Cevallos expedition were given back to Portugal in the Treaty of Paris ( 1763 ) . This was part of a deal to regain Cuba for the Spanish crown , which had been lost in the British expedition against Cuba and which was of much greater importance than these far - away territories .