USS R. B. Forbes (1845) was a steamer acquired by the Union Navy during the American Civil War. Her primary task was to prevent blockade runners from entering, or departing from, the South. R. B. Forbes, a twin-screw steamer built in 1845 — was acquired by the Navy at Boston, Massachusetts on 17 August 1861. Although not formally purchased until September, she was fitted out at Boston and got underway for the Washington Navy Yard on 25 August, Acting Master William G. Gregory in command.