General William Carr Beresford, 1st Viscount Beresford, 1st Marquis of Campo Maior, (; 2 October 1768 – 8 January 1854) was an Anglo-Irish soldier and politician. A general in the British Army and a Marshal in the Portuguese Army, he fought alongside The Duke of Wellington in the Peninsular War and held the office of Master-General of the Ordnance in 1828 in Wellington's first ministry. He led the 1806 failed British invasion of Buenos Aires. Background Beresford was the illegitimate son of the 1st Marquess of Waterford. He was the brother of Admiral Sir John Beresford, 1st Baronet (who was also illegitimate), and the half-brother of the 2nd Marquess of Waterford, Archbishop Lord John Beresford and General Lord George Beresford. Early campaign experience Beresford entered the British Army in 1785 as an ensign in the 6th Regiment of Foot and the next year he was blinded in one eye due to an incident with a musket. He remained in the service being promoted to captain by 1791 with the 69th Regiment of Foot. He distinguished himself at Toulon (1793), in Egypt (1799–1803) and in South Africa (1805). From there crossed the South Atlantic to South America to invade the River Plate region (now Argentina), with a small British force of 1,500 men, departing on 14April 1806. Following his move to Cape Town in Cape Colony, Beresford, spurred on by Home Popham, R.N. (later Rear Admiral Sir Home Popham), decided to attack Buenos Aires in Spanish South America. No attempt was made to gain authorization from the Crown for this undertaking. In the invasion of the River Plate, Buenos Aires was occupied for 46 days. However, the British force could not maintain itself against the army gathered by Santiago de Liniers. After a relentless two-day fight with the Buenos Aires and Montevideo militias between 10 and 12 August 1806, the British were defeated and forced to capitulate. Beresford had to surrender, remaining prisoner for six months; in the end, he managed to escape and arrived in England in 1807. Peninsular War Commander in Chief of the Portuguese Army In that same year Beresford was sent to Madeira, which he occupied in name of the Queen of Portugal, remaining there for six months as Governor and Commander in Chief. The exiled Portuguese Government in Rio de Janeiro, Brazil, whereto the Portuguese Royal Family had set up a Court in exile, realised the