The British Royal Navy had defeated a Franco-Spanish fleet at the Battle of Trafalgar, during October 1805. This left the Spanish with a minimal fleet in their Latin-American colonies. The British saw an opportunity to expand the British economy by having a British colony on the estuary of the River Plate. This became the beginning the Buenos Aires Campaign.
23rd June 1806, Rear-Admiral Sir Home Riggs Popham landed on the left bank of the River Plate with a force consisting of the 71st regiment of Infantry, artillery, and 1,000 men. The British force commanded by General Sir William Carr Beresford, 1st Viscount Beresford.
Subsequently the Marquis Rafael de Sobremonte heard that the British had landed. He sent Spanish troops to Montevideo thinking it would be attacked.
25th June 1806, Quilmes, near Buenos Aires had become captured by the invading British force.
Battle of Buenos Aires 1806
27th June 1806, by the time the British had arrived at Buenos Aires, they found it almost defenceless. The Viceroy of Buenos Aires Santiago de Liniers had fled to Cordoba and became known as a coward by the population.
4th August 1806, Santiago de Liniers landed north of Buenos Aires at Las Conchas with a force of 550 veterans and 400 soldiers.

10th August 1806, finally the north and west points of the city at Miserere and El Retiro had become retaken by Santiago de Liniers.
14th August 1806, General Beresford surrendered. The British had occupied Buenos Aires for 46 days, subsequently being expelled from the city. The British suffered with 100 men dead from sickness, leaving 1,400 of the soldiers weakened.
Battle of Montevideo 1807
Brigadier-General Sir Samuel Auchmuty led his force of 6,000 British troops toward the city of Montevideo.
3rd February 1807, at 2am the weakest part of Montevideo city wall came under heavy bombardment by Royal Navy ships commanded by Admiral Sir Charles Stirling.
The defenders had two bastions adjacent to each other, that gave heavy fire upon the invading force. Captain Renny, 40th Regiment of Foot was killed in the attempt of gaining access to the city via the breach in the wall. However, the British suffered heavy casualties in the constant cross-fire.
Lieutenant Harry Smith of the 95th Regiment of Foot led his men through the breached wall, and also met with heavy resistance. Both Lieutenant-Colonel Brownrigg, 11th Regiment of Foot and Lieutenant-Colonel Vassal, 38th Regiment of Foot had been mortally wounded. The Spainish eventually forced became back after heavy fighting.
However, a number of troops from the 54th Regiment of Foot led a larger British force in a attack that forced the Spainish defenders back. Spainish reinforcements were en route from Buenos Aires which would have given a total of 5,000 men.
The 87th Regiment of Foot along with a company from the 95th Regiment of Foot scaled the walls and attacked the defending Spainish from behind. The 95th Regiment of Foot gained entry to the tower of the city’s cathedral armed with the latest Baker rifle. They fired upon the city’s main fortress, the Ciudadela.
Surrender of Montevideo
By 5am the Governor of Montevideo Ruiz Huidobro surrendered to Brigadier-General Sir Samuel Auchmuty. Afterwards it was reported that by 8am the civilians were going about their normal daily business and mixing with the occupying British soldiers.
Consequently, 500 Spanish troops had been killed, 600 wounded, and 2,000 taken as prisoners of war. The British had 150 dead, including 600 casualties.
September 1807, as a result the British troops had become withdrawn from Montevideo after the British surrender at Buenos Aires in July 1807.
2nd Battle of Buenos Aires 1807
10th May 1807, Lieutenant-General John Whitelocke arrived at Montevideo. He took overall command of the British forces for the Buenos Aires Campaign.

1st July 1807, Santiago de Liniers Spainish troops became overwhelmed by a larger attacking British force. Lieutenant-General Whitelock demanded the citys surrender. The mayor of Buenos Aires MartÃn de Alzaga had prepared defences.
4th July 1807, Lieutenant-General Whitelock ordered the second attack of Buenos Aires. The British troops advanced in 12 columns without any protection from artillery. Fighting broke out on the streets against a defending force of mixed-race militia. Including 686 African slaves, supported by 1st Naval Infantry Battalion and 1st Los Patricios Infantry Regiment.
5th July 1807, the fighting continued in the city. The British 88th Regiment of Foot had cooking pots filled with boiling water and burning oil thrown at them from rooftops. As a result, the British troops had finally became overwhelmed. The areas of Retiro and Residencia became taken at the cost of around 70 British officers and 1,000 troops. However, the city centre was still under the control by the defending Spainish.

The Spainish militia and colonial troops gave a counter-attack, known as the Battle of Plaza del Mercado. Consequently, small parties of British troops became cut off and annihilated in the streets of the city. Brigadier-General Robert Craufurd, Colonel Denis Pack and their 2,000 troops had become forced to retreat to the Convent of Saint Domingo. They became surrounded by 5,000 Spainish soldiers, and surrendered at 4pm.
Aftermath
12th August 1807, Lieutenant-General Whitelock undertook negotiations with Santiago de Liniers, that led to the signing of an armistice. As a result, the Buenos Aires Campaign had come to an end.
Lieutenant-General Whitelock left the River Plate along with the British forces from Buenos Aires, Montevideo, and Colonia. 400 British men seriously wounded became left behind.
However, later in the year when Lieutenant-General Whitelock arrived back to Great Britain, he became court-martialled. He became stripped of his rank as a result of surrendering Montevideo.