Joseph Alexander was born in Acadie (Nova Scotia) the son of Joseph Etienne Landry and Marie-Josephe Bourg of Grand Pre'.

The family was exiled to Oxford, Talbot County, Maryland during the Acadian expulsion of 1755. They came to Louisiana in mid-1760's with mother and three sisters. Joseph Alexandre bought land in 1769 on the west bank of the Mississippi River to become a wealthy plantation owner.

He was a fusilier in Second Company of Acadians, January 15, 1770; lieutenant of militia, 1794; promoted to rank of major, 1804; served as ad interim commandant under Spanish commandant, Croquer, 1799-1803; and he was appointed to the post of Commandant of the second Acadian Coast, by Governor W.C.C. Claiborne.

Joseph later resigned the post of Commandant and served as a member of both the State House of Representatives and State Senate. He owned New Hope Plantation where sugar and corn were major crops. He also owned a retail sugar business.

Married to Isabel Leblance in 1775 (died in 1777) and re-married Anne Bujol.