Italian politician and man of letters who was best known for his part in the diplomatic maneuvers surrounding Giuseppe Garibaldi's (Garibaldi, Giuseppe) expedition in 1860 to liberate Naples and Sicily from Bourbon rule.

Lacaita, a practicing lawyer in Naples, supplied information on Bourbon misrule to the future British prime minister W.E. Gladstone (Gladstone, William Ewart) during the latter's visit to that city in 1851. When Gladstone made the information public the next year, Lacaita was forced to leave Italy, settling first in Edinburgh and then in London, where he served on the faculty (1853–56) of Queen's College. He was knighted in 1859 for his services as secretary to Gladstone during a trip to the Ionian islands.

In 1860, at the request of the Italian leader Count Cavour, Lacaita tried to convince the British foreign minister, Lord John Russell, not to assist Franco-Neapolitan forces in opposing Garibaldi. Lacaita later claimed to have succeeded, but Russell probably never intended to join the coalition. After the downfall of the Bourbons, Lacaita returned to Naples, becoming a deputy and later a senator.