Dundas entered the British Army on 1 December 1797 as a second lieutenant. He served as an engineer officer in the
Anglo-Russian invasion of Holland. He became lieutenant in 1800 and the following year he served in Egypt against the
French campaign, including the
Battle of Alexandria. He was promoted to captain in 1802 and major in 1804. In 1805, he served in the north of Germany with the
Royal Staff Corps. During the
Peninsular War, he saw action at the Battles of
Talavera (1809),
Buçaco (1810),
Fuentes de Oñoro (1811),
Salamanca (1812),
Vitoria (1813),
the Pyrenees (1813), the
Nivelle (1813),
the Nive (1813), and
Toulouse (1814). For his services in the Peninsular War, he received the
Army Gold Medal with Gold Cross and three clasps and was appointed a Knight of the Portuguese
Order of the Tower and Sword in 1814 and a Knight Commander of the
Order of the Bath (KCB) in 1815. Dundas was promoted to Lieutenant-Colonel in 1811, full Colonel in 1821, Major-General in 1830 and Lieutenant-General in 1841. In June 1840, he was made colonel of the
59th (2nd Nottinghamshire) Regiment of Foot. ==Personal life==