William Cocke served as captain in the American Revolution and as one of the Overmountain Men under Colonel John Sevier in the 1780 American victory over British Colonel Ferguson at the Battle of King’s Mountain. Cocke also saw action at the battles of Long Island Flats and Fort Thicketty. He served as one of Tennessee’s first two United States senators (1797–98; 1799–1805). He twice ran for governor. He became judge of the first circuit in 1809 and became the first Tennessee judge to be impeached and removed from office for using his position for private gain in 1812.
In 1813 he was elected to the Tennessee House of Representatives. He left Tennessee in 1814 when President Madison appointed him federal agent for the Chickasaws. He served in the legislature of four states—Virginia, North Carolina, Tennessee and Mississippi—and in the legislatures of Transylvania Colony in Kentucky, the short-lived State of Franklin, and the Territory South of the River Ohio.
In 1794 he sponsored the bill in the legislature of the Territory South of the River Ohio that chartered Blount College, and he is named in the institution’s charter as one of the 18 founding trustees.