Nathaniel Peabody began his career in medicine, practicing in Plaistow and Exeter, New Hampshire. He transitioned into public service during the American Revolution, participating in the raid on Fort William and Mary and serving in New Hampshire's revolutionary assembly. Peabody held various leadership roles, including Adjutant General of the state militia and chairman of the drafting committee for the New Hampshire state constitution. He also represented Rockingham County in the State Senate and ran for higher offices, including New Hampshire governor and U.S. Senate.

Nathaniel Peabody's political career reveals a unique blend of local advocacy and revolutionary fervor, marked by his persistent support for local businesses and medical interests. His military involvement and leadership roles in the militia and Continental Congress showcase a calculated approach to regional defense. Peabody's repeated unsuccessful bids for higher office, juxtaposed with his pivotal role in drafting the New Hampshire constitution, hint at a strategic political identity focused on behind-the-scenes influence rather than public office.