[1] Having spent several months at the military academy, on 27 August the same year Beresford joined the British Army as an ensign in the 6th Regiment of Foot.

[1] Beresford was then promoted to captain on the unattached list of the army on 24 January 1791, subsequently joining the 69th Regiment of Foot in Ireland on 31 May.

When the French Revolutionary Wars began in February 1793, Beresford and his regiment were seconded as marines to the Mediterranean Fleet of the Royal Navy.

Still with the fleet, Beresford then formed part of the force that invaded Corsica in February 1794 alongside a group of Corsican patriots.

A naval bombardment failed to destroy the French-held Torra di Mortella, and so Beresford led a storming party ashore that captured the tower from the landward side.

Beresford was part of the force that recaptured it at the Battle of Blaauwberg in January 1806, commanding a detachment that landed 16 miles (26 km) north of Cape Town.

[3] In that same year Beresford was sent to Madeira, which he occupied in name of Queen Maria I of Portugal, remaining there for six months as Governor and Commander in Chief.

Beresford quickly overhauled the Portuguese forces, bringing them in line with British discipline and organization, and from the General Headquarters (then at the Largo do Calhariz), he dispatched many "daily orders" altering points of the infantry ordnance, creating a general command of artillery, establishing the separation of the battalions, firing incompetent or corrupt officers and promoting or appointing appropriate replacements.

Wellington moved from Coimbra directly to Porto, which he entered on 12 May, and Beresford marched through the Province of Beira, arriving that same day at the banks of the Douro river, in the area of Lamego.

The Second French Invasion of Portugal was defeated and the allied armies moved back to the South, the British concentrating at Abrantes and the Portuguese at Castelo Branco.

With the intention of cooperating with the Spanish against Marshal Claude Victor-Perrin, duc de Bellune, the Anglo-Portuguese forces under Wellesley moved into Spain in the Talavera campaign while Beresford remained on the Águeda river covering the Spanish-Portuguese border.

After Wellesley's return, now as Viscount Wellington, following the Battle of Talavera, Beresford re-entered Portugal, where he distributed the army at various locations and established his General Headquarters in Lisbon.

In the same year (1809), and the one following he made tours of inspection of the corps that were found quartered in the various provinces and he corrected any defects he noticed and established rules for the functioning of the different branches of the military service.

The beneficial results of his efforts were proven at the campaign against Marshal André Masséna in particular at the Battle of Buçaco on 27 September 1810 where the Portuguese troops played a prominent part, and also in the defence of the Lines of Torres Vedras).

At the beginning of July 1811, Beresford was again in Lisbon, but he was subjected to fits of "nervous breakdowns", as described by Brigadier Benjamin D'Urban, Quartermaster-general of the Portuguese Army.

On 22 July 1812, the important Battle of Salamanca was fought, giving the Anglo-Portuguese forces a decisive victory over the French under Marshal Marmont.

During that conflict he had been present at the battles of A Coruña, Busaco, Albuera, Badajoz, Salamanca, Vitoria, the Pyrenees, Nivelle, Nive, Orthez and Toulouse.

Beresford took a high hand in his dealings with Gomes Freire de Andrade (1817) and, put into a difficult situation, he returned to Brazil, obtaining from John VI the confirmation of the powers he had already attained, which he desired to see amplified.

When he returned to Portugal, the Liberal Revolution of 1820 intervened; the British officers, for the most part, had been discharged, and the government would not even consent that Beresford could disembark.

[6] Napier, in his History of the Peninsular War, severely criticised the tactics of Beresford at the Battle of Albuera, which gave origin to a heated correspondence between the Marshal and the historian.

Also of interest is the Colecção das Ordens do Dia (Collection of Orders of the Day) produced by Beresford's general headquarters nos Anos de 1809 a 1823 (for the years 1809 to 1823), Lisbon, 13 Vol.

As a reward for his services in the fight against the French he was raised to the peerage as Baron Beresford, of Albuera and Dungarvan in the County of Waterford, on 3 May 1814.