After serving as a surgeon's assistant in the American Revolutionary War, he moved to Natchitoches, Louisiana to work as a contract surgeon. From 1805 to 1815, Sibley was also the official Indian Agent of New Orleans Territory. Later in life, he served as a Senator in the Louisiana State Senate, as well as a colonel of a militia, a cattle farmer, a cotton planter, and a salt manufacturer.
Born in 1757, Sibley lived in Suffolk County, Massachusetts, until moving to Louisiana in 1803. During the Revolutionary War, John Sibley was a surgeon's assistant, giving him the experience to continue his practice after the war, however, in 1784, John moved to Fayetteville, North Carolina and started his own newspaper, the Fayetteville Gazette. In 1791, Sibley married a widow named Mary W. Winslow.
In 1803, after the Louisiana Purchase, Sibley moved to Natchitoches and was hired by the Army as a contract surgeon for five years. From 1805 to 1815, Sibley was also the official Indian Agent of New Orleans Territory. His diary and sketches of Native American tribes survive as evidence of early American Louisiana.
As well, letters from Sibley to Thomas Jefferson have survived. In them, Sibley described important political moments in early Louisiana, and gave the President reports on his one-on-one relationship with the inhabitants of the Louisiana territory, including Native Americans, Spaniards, and French. His letters also reveal the tension within the US government on how to handle the new territory, and whether or not they should heavily guard the border between the two.
In his position of Indian Agent of New Orleans, he was instructed to stay in contact with the Governor and the War Department, with populations, the names of important people, and their overall living situations, as well as to help smaller tribes prepare for land surveying by the government. Along with all of these duties, Sibley was to report any Native American tribes which seem that they would ally with either the American or Spanish forces within the area. As Sibley's time in the Louisiana Territory passed, his family, who still lived in North Carolina, began suffering the rumors that he had abandoned them, however, Dr. Sibley had written a letter in 1808 that read, "I am making arrangements to remove my family from North Carolina to this place." However, by the time of Mary Winslow's death in 1811, they had yet to be removed.
Due to these connections, Dr. Sibley became involved with a myriad of jobs, including being part of the Louisiana State Senate, becoming a colonel of a militia, a cattle farmer, a cotton planter, and a salt manufacturer before passing away in 1837.