He went to England to study law and was admitted to the Middle Temple on September 27, 1753.
His first appearance in history was as a member of the Virginia Convention of 1776. He was in the House of Burgesses of the new state in 1777, and in 1778-79 he was a delegate to the Continental Congress. His position in that body is indicated by the fact that he was one of the framers of the Articles of Confederation; and of course he was a signer of that instrument. In the war he was lieutenant-colonel of cavalry in the Virginia line, during the years 1778-81. That he was highly valued by Washington is shown by an intimate letter which the commander-in-chief wrote to him from Valley Forge.
In the final campaign of 1781 he aided in repelling the British invasion of his state. He contributed supplies to the cause, and suffered losses of property; his home at Battersea, near Petersburg, was a convenient stopping-place for the British force under Gen. Phillips.
He was a good writer, well informed on current affairs.
Banister was first married to Patsy, daughter of Col. Theodoric Bland, and his letters figure frequently in the extensive correspondence of the Bland Papers, his second marriage was to Anne, daughter of John Blair of Williamsburg.