In March, 1776, he attended the Convention of Virginia held in Richmond. Here he moved that "this colony be immediately put in a state of defence, and that a committee be appointed to prepare a plan for embodying, assigning, and disciplining such a number of men as may be sufficient for that purpose." Bland, Harrison, Pendleton, and Nicholas, all vigorously opposed these resolutions as leading inevitably and logically to revolution and separation; but Henry, in a storm of patriotic, eloquent enthusiasm, carried everything, uttering those deathless sentences, "Our brethren are already in the field! Why stand we here idle. What is it that gentlemen wish? What would they have?
"Is life so dear or peace so sweet, as to be purchased at the price of chains and slavery?
"Forbid it, Almighty God! I know not what course others may take, but as for me, give me liberty or give me death!"
The resolutions were carried and Henry made chairman of the committee to organize the colony. He proceeded with great vigor to form companies of cavalry or infantry in every county. On April 20, 1775, Lord Dunmore, the royal governor, seized the powder of the colony and placed it on the armed schooner Magdalene. The country rose at once. Henry, as captain, marched the independent company of Hanover on Williamsburgh, to compel the governor to pay for or restore the powder. Five thousand armed men were marching from the counties to reinforce him, when Lord Dunmore, through the intercession of Peyton Randolph, paid Henry for the powder and induced the volunteers from Hanover, Frederick, Berkeley, and other counties to return to their homes. As soon as they had returned, Dunmore issued a proclamation denouncing Henry and his comrades as traitors and rebels.
Henry was elected by the Virginia Convention one of the deputies to the second Continental Congress. He was also elected colonel of the first Virginia Regiment, and "commander-in-chief of all the forces raised and to be raised for the defence of the colony." Lord Dunmore having erected a fortification south of Norfolk, at Great Bridge, Colonel Woodford, with the second Virginia Regiment, was sent by the Committee of Safety to drive him away, which he did promptly and well. Henry claimed the right to command this expedition himself, but his claim was not admitted by the committee, and his authority was disclaimed by Colonel Woodford. Henry insisted upon having the question of rank between them decided, and the committee decided in favor of Colonel Henry. Yet when brigadiers were selected by Congress to command the troops of Virginia in the Continental Army, Andrew Lewis was made brigadier, Henry colonel of the first regiment. He promptly refused the Continental commission, and resigned the one held in the service of Virginia. Henry's conduct was justified in the opinion of his contemporaries and of posterity. He had led the colony at the risk of life and fortune, he had organized and led the first movement of troops against the royal authority, he had been appointed commander-in-chief and colonel of the First Regiment, and then had been superseded in command by another, without excuse or justification. He was thus driven out of the military service by petty intrigues and small jealousies of smaller men, and the country deprived of his great abilities in the military field.
On May 15, 1776, the Virginia Convention instructed their deputies in Congress "to declare the United Colonies free and independent States," and on June 29th adopted a form of State government and elected Mr. Henry governor. During the winter of 1776-77 was the darkest period of the revolution, and it has been charged that it was proposed to create him dictator; but his friends have always denied this, and it seems with truth, for he was re-elected governor, May 30th, 1777. He was a firm supporter of General Washington through all the trials of that period, and firmly stood by him against the intrigue in the army to supersede him with Gates. He was again elected governor in the spring of 1778, and the next year declined a re-election because in his opinion he was ineligible. His wife, Miss Shelton, died in 1775, leaving him the father of six children, and in 1777 he married Dorothea, daughter of Nathaniel W. Dandridge.
After the expiration of his gubernatorial service he retired to his estate in Henry County. He was elected to the General Assembly for that County in 1780, and he continued to represent it until after the revolution. He took the ground of amnesty to the Tories and the resumption of commercial intercourse with Great Britain. In 1784, he introduced and urged the passage of a bill to promote inter-marriages with the Indians, which failed to pass from his being again elected governor on November 17, 1784, for the term of three years.
He declined a re-election, and was appointed one of the deputies from Virginia to the Constitutional Convention to meet in Philadelphia. The order of appointment being George Washington, Patrick Henry, Edmund Randolph, John Blair, James Madison, George Mason and George Wythe. He, however, was too poor to perform the duties of the office and was obliged to return to the practice of the law. He was sent as a member from Prince Edward to the convention to consider the Federal Constitution which had been framed at Philadelphia. The convention met at Richmond, June 2, 1788.
It was composed of the most illustrious men that Virginia ever produced, and was probably the ablest body that ever convened in any country in any age. James Madison, John Marshall, James Monroe, Edmund Pendleton, George Nicholas, George Mason, Jarvis, Grayson, and Henry, Lee, and Randolph were among the members. Henry vigorously opposed the ratification of the new constitution on the ground that it would establish a government of the people in place of a government of the States, and would create a consolidated government with omnipotent power, without check or balance, and lead to a great and mighty empire and an absolute despotism. The Federal party carried the ratification under the lead of Madison and Marshall by a majority of ten.
In the ensuing General Assembly Henry opposed the election of Madison as one of the first senators under the new constitution, and secured that of Richard Henry Lee and Grayson to represent Virginia in the first Congress. He also drafted and had passed resolutions calling upon Congress to call a Constitutional Convention of the States to cure by amendments the many defects in the Federal Constitution which were indicated by the amendments proposed to it by Virginia. The Convention was never called, but ten of the amendments were adopted by Congress and ratified by the States.