William was born at Poplar Forest in 1799. Unlike his grandfather and mother, he rebelled violently against slavery. In 1812, Jefferson sent him to Monticello to learn a trade. His sister Sally and cousin Maria journeyed with him to work in the textile shop. Two of his uncles, and other slaves from Poplar Forest, lived at Monticello too.

William showed promise as a craftsman. Yet by age 18, he had a bad reputation. In late 1817 Jefferson removed him from the supervision of enslaved master carpenter John Hemmings, assigning him to make barrels.  Within two months, having proved to "be so ungovernable and idle" that he could no longer remain in the cooper's shop, William was sent back to Poplar Forest to work in the fields.

In the fall of 1819, he attacked a Poplar Forest overseer. The man was not seriously hurt. Following the attack, William ran away to Monticello to argue his case.  efferson's farm manager urged him to dispose of the young man. How or if Jefferson punished William is not known, but he sent him back to Poplar Forest.

Three years later, William and two others were arrested and tried for attacking another Poplar Forest overseer and for conspiracy to rebel. William was convicted of the first charge and sentenced to be burned on the hand and publicly whipped. The others were acquitted due to insufficient evidence. Following the trial, Jefferson sent the three men, along with a fourth slave believed to have taken part in the attack, to Louisiana. He hoped this would deter other slaves from rebellious behavior. By early 1824, all had died except William. He tried again to run away, and was caught in New Orleans and sold.