He was the son of Anthony Morris (14 Feb 1705/06–2 Oct 1780) and the former Sarah Powell (29 Jun 1713–10 Apr 1751).

When the first troop of Philadelphia city cavalry was organized, no fewer than twenty-two members of the club were enrolled in its ranks.

With Morris as its captain (because the first captain chosen, Abraham Markoe, was forbidden to fight because of his Danish citizenship), the troop reported for duty in the Continental Army and served through the campaign of 1776–77, seeing action in the battles of Trenton and Princeton,[2] in which latter engagement Samuel's brother Anthony, ensign of the Pennsylvania Associators,[3] was killed.

On temporarily relieving the command from duty in January, 1777, Washington returned his "most sincere thanks to the captain," and added that, although the troop was "composed of gentlemen of fortune," its members had "shown a noble example of discipline and subordination."

For thus taking part in the Revolution, Captain Morris was disowned by the Quakers, but he continued until his death to wear the dress and use the language of that sect, worshiping with them regularly.