HMS Mars was a 74-gun third-rate ship of the line of the Royal Navy, launched on 25 October 1794 at Deptford Dockyard.

Hercule attempted to escape through the Passage du Raz but the tide was running in the wrong direction and she was forced to anchor, giving Captain Hood the chance to attack at close quarters.

The two ships were of equal strength, but Hercule was newly commissioned; after more than an hour and a half of bloody fighting at close quarters she struck her flag, having lost over three hundred men.

Mars fought at Trafalgar where she was heavily damaged as she took fire from five different French and Spanish seventy-fours.

In 1806, on service in the Channel fleet she took part in an action off Chasseron which led to the capture of four French ships.