Jonas was born in to a Jewish family in New Orleans, Louisiana. He enlisted in the army during the early days of the Civil War and initially served in the Fenner Artillery. He was later promoted to the rank of major. He was a member of the Louisiana state house of representatives in 1865.
Following the war, he served as a U.S. Senator during Reconstruction as a Democrat from 1879 to 1885. He was the second Jewish U.S. Senator from Louisiana, the first having been Judah P. Benjamin, who served Louisiana in the U.S. Senate prior to the American Civil War.
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sv:Benjamin F. Jonas