Born in Sandwich, New Hampshire, Peabody established himself in New York City as a young man.

[1][2] In 1834, Peabody began the study of law in Baltimore, in the office of Nathaniel Williams, then United States District Attorney of Maryland.

After two years, Peabody moved to Massachusetts and pursued his studies in the Law School of Harvard College.

In 1839, he moved to New York, where he entered began the practice of law, and "became identified socially, through domestic ties, with the most eminent families of the metropolis".

[4] Peabody was commissioned Chief Justice of Louisiana,[5] appointed court officers,[3] and drew a salary, but never heard a case.