After 1820, the day-to-day duties of the United States Navy involved dealing with smugglers, pirates, and the illegal slave trade and so deploying the large ships of the line was deemed unnecessary. Also, the successful completion of treaties with both England and Spain demilitarized the Great Lakes and stabilized the country’s southern border, easing concerns about a future foreign war. ‘A constabulary navy: pirates, slavers, and manifest destiny (1820–1850)’ describes the peacetime navy activities carried out by small squadrons of sloops and schooners acting as a constabulary force on distant stations abroad, mainly in the Mediterranean, but also in the West Indies, off Africa, in the Pacific, off Brazil, and in the East.