James Moore gained military experience in colonial North Carolina as a captain at Fort Johnston and during the Cherokee conflict. He also served in the colonial assembly and commanded artillery for Governor William Tryon at Alamance in 1771. Although he had helped suppress the Regulators, he opposed parliamentary taxation and became active in the Cape Fear resistance movement. He joined committees and helped organize provincial congresses.

In 1775 Moore received command of the 1st North Carolina Regiment. During the Loyalist mobilization of early 1776, he coordinated movements intended to prevent Highland recruits from joining British forces on the coast. His maneuvering helped force the Loyalists toward Moore's Creek Bridge, where Richard Caswell and Alexander Lillington defeated them on February 27. Moore was absent from the battle itself, but directed the wider campaign and captured fugitives and supplies.

Congress promoted him to brigadier general in March 1776. He maintained defenses around Wilmington against the threatened British invasion and subsequently moved his troops toward South Carolina. When Charles Lee left the region, Moore briefly exercised senior command in the Southern Department. Congress later ordered the North Carolina regiments north to reinforce Washington. Illness prevented Moore from leading them there, and he died at Wilmington in 1777. His service included organizing a regiment and coordinating the campaign against a major Loyalist rising.