Battle of Colonia del Sacramento (1807)

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. The artillery train was left in Real San Carlos.^[3] The advance was, in the opinion of contemporary writers and historians like Domingo Matheu, Ignacio Nuñez, Bartolomé Mitre and Vicente Fidel López, unprofessional at best.^[5] No forward parties were sent to sweep the area, no previous reconnaissance was performed before the assault. To make things worse, a member of the Catalonian regiment accidentally discharged his rifle, putting the British on alert.^[6] Notwithstanding this incident, the Spanish infantry was able to overwhelm a British post, but no further progress was possible because the assaulting troops scattered into the settlement instead of concentrate their efforts on the enemy's positions.^[5] This manoeuver allowed a British company to attack the flanks and rout the main Spanish force.^[3] de Elìo withdrew to Real San Carlos to protect his artillery and ordered a general retreat to Calera de las Huèrfanas, 70 kilometres (43 mi) away.^[3] The Spanish expedition lost eight men and suffered 16 wounded, while one soldier from the British garrison was killed and two officers and a private injured.^[4]

Colonel de Elìo was heavily criticized by his conduct of the action against Colonia. He was accused of mounting a reckless assault without previous knowledge of the terrain, giving the enemy more than enough time to react.^[5] After the withdrawal, de Elío established his headquarters at San Pedro, where the expeditionary army was once again attacked by the British and forced to retreat to Buenos Aires. There, they prepared for a last ditch defense.^[2]