The matter escalated in February 1776 when two Portuguese fleets under Robert MacDouall and Jorge Hardcastle landed troops near the fortress of Rio Grande de São Pedro, and started shelling the Spanish fort.

On 20 March, Cevallos sailed towards his second target, Rio Grande de São Pedro, but the fleet was dispersed by a storm and had to return to Montevideo.

The new captain, who also played an important role in capturing the ship, was an Englishman in Portuguese service, Arthur Phillip, who later founded Port Jackson (Sydney).

After taking Sacramento, Cevallos marched towards Rio Grande de São Pedro and joined forces with the troops of Juan José Vertiz in Santa Teresa but was ordered to turn back as peace negotiations had started.

On 24 February 1777, King Joseph I died, and his daughter and successor Maria I dismissed Pombal and concluded on 1 October the First Treaty of San Ildefonso with Spain.

In return, Spain acknowledged that the Portuguese territories in Brazil extended far west of the line that had been set in the Treaty of Tordesillas.