At the outset of the Revolution, although an officer of the Proprietary Government, William Maclay took a prominent and active part in favor of independence, not only assisting in equipping and forwarding troops to the Continental Army, but marched with the associators which participated in the Battles of Trenton and Princeton. He held the position of assistant commissary of purchases.

During the “Great Runaway,” following the Wyoming massacre, July 3, 1778, William Maclay fled with his family from Sunbury to Harris’ Ferry, and in a letter to the president of the Executive Council he gave a very graphic picture of the distress. Again after the attack and destruction of Fort Freeland by the British, Tories and Indians, July 28, 1779, Maclay again wrote to the seat of government in which he described the forlorn situation of the frontiers. In a later letter he deplored the removal of soldiers from the West Branch Valley, where the Indians had committed such terrible depredations.

In 1781 he was elected to the Assembly, and from that time forward he filled the various offices of member of the Supreme Executive Council, Judge of the Court of Common Pleas, deputy surveyor, etc. After the Revolution he made a visit to England in the interest of the Penn family.

In January, 1789, he was elected to the United States Senate, taking his seat there as the first Senator from Pennsylvania. He drew the short term, and his position terminated March 3, 1791, his colleague, Robert Morris, securing the long term.

Maclay’s election to this body raised him upon a higher plane of political activity, but contact with the Federal chiefs of the young Republic only strengthened his political convictions, which, formed by long intercourse with the people of Central Pennsylvania, were intensely democratic.

Maclay differed with the opinions of President Washington; he did not approve of the state and ceremony attendant upon the intercourse of the President with Congress, he flatly objected to the presence of the President in the Senate while business was being transacted, and in that chamber boldly spoke against his policy in the immediate presence of President Washington.

Maclay was the original promoter and later the actual founder of the Democratic Party. Long before Thomas Jefferson’s return from Europe, William Maclay assumed an independent position, and in his short career of only two years in the Senate propounded ideas and gathered about him elements to form the opposition which developed with the meeting of Congress at Philadelphia, October 24, 1791, in a division of the people into two great parties, the Federalists and Democrats, when, for the first time, appeared an open and organized opposition to the Administration.

The funding of the public debt and chartering the United States Bank were opposed by Maclay, even at a sacrifice of personal popularity, for he was succeeded in the Senate by James Ross, a pronounced Federalist.

While in the Senate Maclay preserved notes of his discussions, both in open and executive sessions, with observations upon the social customs of the statesmen of the Republic, which have since been published.

On his retirement from the Senate William Maclay resided on his farm adjoining Harrisburg, where he erected a fine stone mansion, afterward, for many years, occupied by the Harrisburg Academy.