[2] On September 7, 1822, the Prince Regent of Brazil proclaimed independence from Portugal (known as Grito de Ipiranga).
When a new war was declared between the Empire of Brazil and the Argentine Republic, Drummond requested the withdrawal of the Imperial Brazilian Navy on February 8, 1826, and a month later he embarked for the Río de la Plata in the North American schooner with Captain Deverians, arriving in Montevideo on March 21.
At the end of 1826 Drummond was finally able to join the Argentine squadron operating on the Uruguay River and on January 24, 1827 he was appointed captain, receiving command of the Maldonado Goleta, formerly the Leal Paulistana that had been captured from the Brazilians on 21 September on Gorriti Island.
At the Battle of Juncal (February 8 and 9, 1827), Drummond fought against the schooner Bertioga, commanded by Lieutenant John Broon.
For his bravery in battle, he was awarded the Silver Shield medal and promoted to Sergeant Major on March 23, 1827.