Later in 1783 Armstrong returned home to Carlisle and became an Original Member of the Pennsylvania Society of the Cincinnati. He was named the Adjutant General of Pennsylvania's militia and also served as Secretary of the Commonwealth of Pennsylvania under Presidents Dickinson and Franklin. In 1784, he led a military force of four hundred militiamen into a controversy with Connecticut settlers in the Wyoming Valley of Pennsylvania. His tactics enraged the nearby states of Vermont and Connecticut, which sent their own militia into the area. Timothy Pickering was dispatched to forge a solution to the difficulty, and the settlers were able to keep title to the land they had tamed. In 1787 and 1788 Armstrong was sent as a delegate for Pennsylvania to the Congress of the Confederation. The Congress offered to make him chief justice of the Northwest Territory. He declined this, as well as all other public offices for the next dozen years.
