After the conquest of Montevideo by the British expedition under the command of Lieutenant General John Whitelock on 3 February 1807, Rear-Admiral Charles Stirling dispatched the sloop HMS Pheasant to support the capture of the Spanish stronghold of Colonia del Sacramento, that was carried out on 16 March by infantrymen of the 2nd Battalion 95th Rifles without resistance.

[3] The commander of the Rifles, Colonel Dennis Pack, deployed groups of 200 or 300 men on several key points around the fortress and mounted chevauls de frise to improve the stronghold defenses.

[3] Colonel Francisco Javier de Elío, the military commander of the Banda Oriental, managed to flee Montevideo and reached Buenos Aires, where he summoned the main Spanish officers to a war council which decided to gather 500 volunteers, most of them from the Patricios Regiment.

[4] On 21 April, when the expedition reached Real San Carlos, de Elío learned that the British army had made a thrust to the northwest in the belief that incoming Spanish forces were approaching from that direction.

de Elío, confident that the British garrison would be exhausted after a full day of march, ordered his troops to move to Colonia through the countryside at night, crossing ravines and reedbeds.