Born on January 1, 1819, in Saco, Maine,[1] Shepley attended Harvard University, received an Artium Baccalaureus degree in 1837 from Dartmouth College and read law in 1839.

[1] He served as a Brigadier General in the United States Army during the American Civil War from 1861 to 1865.

[2] He was assigned to the Department of the Gulf, commanding a brigade during the New Orleans campaign from April 18, 1862, to May 1, 1862.

[2] He briefly headed a district in Virginia and then served as chief of staff of XXV Corps, in the Army of the James.

[1] He was confirmed by the United States Senate on December 22, 1869, and received his commission the same day.