Thomas Pleasant Dockery was born in Montgomery County, North Carolina on 18 December 1833 to Colonel John Dockery who participated in the Indian removals in North Carolina.
His father moved first to Tennessee and then to Columbia County, Arkansas where he established a large plantation. John Dockery also played a role in establishing the first railroad in Arkansas.
At the outbreak of the Civil War, Thomas Dockery received a commission in the Confederate States Army as Colonel of the 5th Arkansas State Troops. Dockery led this unit at the Battle of Wilson's Creek in southwest Missouri. Dockery was soon given command of the 19th Arkansas Infantry Regiment.
After the Battle of Pea Ridge most Confederate units were withdrawn from Arkansas to the east side of the Mississippi River. Dockery and his unit participated in the Battle of Corinth and led a brigade during the battles around Vicksburg such as the Battle of Champion's Hill. He was captured at Vicksburg where he was paroled.
Dockery recrossed the river with General Sterling Price and for a time Dockery was in command of central Arkansas. On 10 August 1863 he received his commission as Brigadier General and raised an Arkansas brigade which he led in the Red River Campaign and participated in the Battle of Marks' Mill and the Battle of Jenkins' Ferry.
In May of 1865 Dockery signed the instrument of surrender which surrendered all remaining Confederate forces in Arkansas. Dockery lost his remaining propery during the war.
After the war Dockery became a civil engineer and lived in Houston, Texas.
Thomas Pleasant Dockery died in New York, New York on 27 February 1898. He is buried at Natchez, Mississippi.