Trained as a doctor at the University of Pennsylvania School of Medicine, earning an M.D. in 1835, Eddy moved to Mishawaka, Indiana after graduation in 1835. There, he practiced medicine until 1847, when he changed his focus to law, passing the bar and moving to South Bend, Indiana. His efforts shifted again three years later, when he commenced a political career in the Democratic Party with a post in the Indiana State Senate. After holding that position and several other local offices, he was elected to the 33rd Congress, defeating Schuyler Colfax. Eddy served only one term in this office, as he was in turn defeated by Colfax when he attempted to run for re-election. Undaunted, Eddy continued his political career as Attorney General of the Territory of Minnesota, serving as an appointee of President Franklin Pierce in 1855.
The outbreak of the American Civil War marked a new phase of Eddy's life, as he organized the 48th Indiana Infantry and received a commission as its colonel. Eddy served in this capacity for two years, but received disabling wounds in Mississippi at the Battle of Iuka and left the service in July 1863. Despite the wounds, he was fortunate, as 119 of his 420 men were killed or wounded in the engagement after Eddy bivouacked his unit in directly front of an enemy artillery location.
After the close of his military career, Eddy was Indiana's collector of internal revenue from 1865 to 1870, and then its Secretary of State of Indiana from 1870 to 1872, before dying suddenly as a result of a heart condition on January 28 of that year. An Episcopalian, Eddy was buried in City Cemetery.
- "Penn and the U.S. Congress (D-H), University of Pennsylvania University Archives". upenn.edu. Archived from the original on 2018-04-23. Retrieved 2015-04-21.
|U.S. House of Representatives|
Graham N. Fitch
| Member of the U.S. House of Representatives
from Indiana's 9th congressional district
Max F. A. Hoffman
| Secretary of State of Indiana
William W. Curry