Born in Turin, he entered the Sardinian army in 1823, and was a captain in March 1848, when he gained distinction and the rank of major at the siege of Peschiera [it].

On 5 August 1848 he liberated Charles Albert of Sardinia from a revolutionary mob in Milan, and in October was promoted general and appointed Minister of War.

In 1860 he was sent to Berlin and Saint Petersburg to arrange for the recognition of the kingdom of Italy and subsequently he held the offices of governor of Milan and royal lieutenant at Naples, until, in September 1864, he succeeded Marco Minghetti as premier.

[1] In April 1866 La Marmora concluded a military alliance with Prussia against Austria-Hungary, and, on the outbreak of the Third Italian War of Independence in June, took command of an army corps.

Accused of treason by his fellow countrymen, in particular by other high-rank generals, and of duplicity by the Prussians, he eventually published in defence of his tactics (1873) a series of documents entitled Un po' più di luce sugli eventi dell'anno 1866 ("More light on the events of 1866"), a step which caused irritation in Germany, and exposed him to the charge of having violated state secrets.