Built to the order of the French government in order to inaugurate, along with six other brand-new vessels, its newly-created postal packet service in 1836, Léonidas was laid down in the naval dockyard at Brest. Named for the ancient King of Sparta who died a hero's death she was registered at 633 tons gross (374 net) and measured 187 feet in length with a 29 foot beam. Fitted with a 160hp. engine to give her a cruising speed of 9 knots, she carried a crew of four officers assisted by 32 sailors and had accommodation for 26 passengers.
After fifteen years of reliable service Léonidas - and, indeed, all six of her sisters - were sold to Compagnie des Messageries Maritimes of Marseilles for commercial use. Her new owners took delivery of her on 16th October 1851 and placed her on their regular Marseilles to Constantinople run, a service she helped maintain until 1855 when she was relegated to harbour duties at the 'Golden Horn'. Eventually returning to her home port of Marseilles early in 1858, she was broken up in Joliette in May of the same year.