Named for the Whitworth family of Mayfield, the farm on which it was built, this outpost (a quarter-mile east) and Fort Gregg, 400 yards to the south, were constructed to protect the western approaches to Petersburg during the 1864-1865 siege. On 2 April 1865, when Gen. U.S. Grant's army attacked the city after turning Gen. R.E. Lee's flank at Five Forks the day before, the forts were the scene of intense fighting. The Union XXIV Corps captured the two positions, suffering 714 casualties. The Confederates lost about 300 men in a stubborn defense that delayed the Union advance for two hours, enabling Lee to withdraw his army safely that night and begin the westward march that ended a week later at Appomattox Court House.