<P> The settlement of Baton Rouge by Europeans began in 1721 when a military post was established by French colonists . Since European settlement, Baton Rouge has been governed by France, Britain, Spain, Louisiana, the Republic of West Florida, the Confederate States, and the United States . In 1755, when French - speaking settlers of Acadia in Canada's Maritime provinces were driven into exile by British forces, many took up residence in rural Louisiana . Popularly known as Cajuns, the descendants of the Acadians maintained a separate culture . During the first half of the 19th century, the city grew steadily as the result of steamboat trade and transportation . </P> <P> Baton Rouge was incorporated in 1817 . In 1822, the Pentagon Barracks complex of buildings was completed . The site has been used by the Spanish, French, British, Confederate States Army, and United States Army and was part of the short - lived Republic of West Florida . In 1951, ownership of the barracks was transferred to the State of Louisiana, and in 1976 it was placed on the National Register of Historic Places . </P> <P> In 1846, the state legislature designated Baton Rouge Louisiana's new capital to replace "sinful" New Orleans . The architect James Dakin was hired to design the Capitol building in Baton Rouge, with construction beginning in late 1847 . Rather than mimic the federal Capitol in Washington, as many other states had done, he designed a capitol in Neo-Gothic, complete with turrets and crenellations, and stained glass, which overlooks the Mississippi . It has been described as the "most distinguished example of Gothic Revival" architecture in the state and has been designated as a National Historic Landmark . </P> <P> By the outbreak of the Civil War, the population of Baton Rouge was nearly 5,500 . The war nearly halted economic progress, except for businesses associated with supplying the Union Army occupation of the city beginning in the spring of 1862 . The Confederates at first consolidated their forces elsewhere, during which time the state government was moved to Opelousas and later Shreveport . In the summer of 1862, about 2,600 Confederate troops under generals John C. Breckinridge (the former Vice President of the United States) and Daniel Ruggles tried in vain to recapture Baton Rouge . </P>

When did baton rouge become the capital of louisiana