Owing to the financial misfortunes of his father, who was a merchant, he was early thrown upon his own resources and at the age of seventeen removed to Raleigh, where he became a surveyor. He was also a lawyer, and, being a versatile man, a good speaker, and highly regarded, he held political offices at an early age. He was deputy-surveyor of the colony, clerk of Orange County, and in 1754-71 a member of the North Carolina Assembly. During this long term of legislative service he was very active, particularly in reforming the courts of law. In the last two years he was speaker of the Assembly. During the insurrection of the Regulators in 1771 he served under Gov. Tryon at the battle of Alamance, commanding the right wing. During the Revolution, Caswell was prominent in various lines. He presided over the provincial congress, and also over the convention which prepared the state constitution, being a member of the committee which framed that document. He was a delegate to the Continental Congress 1774-76. In the army he was colonel of North Carolina Partisan Rangers 1776-77, and was major-general of the state militia from 1780 to the end of the war. His military opportunity came at the battle of Moore's Creek, February 27, 1776. In this action Colonels Caswell and Lillington with about 1, 100 men repulsed a Loyalist army of about 1, 600 led by the Scotch Highlander McDonald. The victory was complete, and decisive--for some years--of the war in North Carolina. McDonald and about 900 of his army were taken prisoners, and the captures included money, arms, and ammunition (see, for the numbers, R. D. W. Connor, Revolutionary Leaders, and North Carolina Colonial Records). Caswell had shown skill, and received the thanks of Congress. While governor in 1777 he received a letter from Washington, urging strong measures in dealing with deserters. His popularity suffered a temporary eclipse after the battle of Camden. In this disastrous action Caswell commanded the North Carolina militia. When his men broke and fled, Caswell, having attempted vainly to rally them, shared in Gates's rapid flight northward. He was superseded for a while by Gen. Smallwood in the command of the state militia, but his influence in the state was soon recovered. He held the offices of speaker of the Senate, comptroller-general, and governor for a second time, 1785-87. While governor he was chosen delegate to the Federal Convention, but declined to serve. He showed his interest in its actions, however, by asking for information that might be of use to the Convention, and by correspondence with the delegates from his state in regard to the proceedings. When the state convention met for ratification, Caswell's influence was thrown against the new Federal Constitution. While holding his last political office as speaker of the Assembly, he was stricken with paralysis, and died a few days later at Fayetteville.