He was born in 1755 in Prince William County, Virginia, the son of Jane Glascock Purcell and her husband John Simms.

Simms received a private education suitable to his class and was studying law as the American Revolutionary War began.

Still serving as such on August 29, 1814, Simms negotiated an arrangement with Captain James Gordon, whose frigate Seahorse led a British armada up the Potomac River, anchored off Alexandria's port, and demanded all ships and cargo awaiting export.

They took 21 vessels, as well as 13,786 barrels of flour, 757 hogsheads of tobacco, and tons of cotton, tar, beef, sugar and other merchandise valued at $100,000 without a shot being fired.

In the 1787 Virginia Census, Simms owned two enslaved children and four adults in Alexandria, and property (including livestock) in Fairfax County, but no slaves.

His son-in-law Cuthbert Powell served as Alexandria's mayor before moving to Loudoun County, which he represented in both houses of the Virginia General Assembly and for a single term in the U.S. Congress; two of his grandsons died fighting for the Confederacy, one at each of the Battles of Manassas.