General Carlos María de Alvear had moved to the border with Brazil on January 20, 1827, attacking some small towns and villages and successfully trying to bring Brazilian commander Felisberto Caldeira Brant, Marquis of Barbacena, to him.

A Brazilian Imperial Army force encounters Alvear's Argentine–Uruguayan troops on February 20 in the Battle of Ituzaingo (Passo do Rosário).

Fought in vicinity of the Santa Maria River, in a valley of small hills where a stream divides the valley into two, the battle ends with a tactical victory for the Republicans, since Barbacena cannot march on Buenos Aires, as he had planned, but with no strategic gain for either side.

The war will continue for another year with inconclusive frays between small groups of men on each side, but only the disputed province will gain anything: in 1828, a treaty will be signed between Brazil and Argentina that grants its independence as present-day Uruguay.