Born in Charleston to Myer and Esther Moses, Montgomery married his first cousin Catherine Phillips in Philadelphia in 1832 and went into law partnership with his brother Franklin I. Moses in Sumter, South Carolina. After the Civil War, Montgomery and Catherine moved to Newberry. In 1871, during Reconstruction, he was elected circuit judge, while his brother served as chief justice of the South Carolina Supreme Court and his nephew, Franklin J. Moses, Jr., became governor.