Born at Buckingham County Court House in Buckingham County, Virginia, he was the sixth of eleven children born to John Thomas Bocock (a farmer, lawyer, clerk of the Appomattox County Court House and friend of Thomas Jefferson) and Mary Flood (of a powerful and distinguished family which later produced Harry Flood Byrd), Thomas Bocock was educated by his father and other private teachers as a child. He attended Hampden–Sydney College, where he befriended Robert L. Dabney (his rival for class valectedorian) and graduated in 1838.