Armistead was born in 1838 as the son of Virginian farmers Lawson Turner and Frances Taylor Thompson. He was a teacher in the school before the war. At the age of 23, he voted for the secession of southern states and joined the newly established 8th Virginian Infantry Regiment, later known as the "bloody eighth", in Dranesville by Capt Thrift. Since then, he has been fighting as a Confederate soldier. According to his company muster roll, he was wounded during the battle of Gaines Mill in 1862 and was captured by the Union army. The record suggested that he was treated in the Union hospital and was offered honorary parole and released. He promised the Union that he will simply go home and never to rejoin the Confederate war effort. However, he broke this promise by returning to his unit in Rappahannock in May 1863. His unit arrived in Gettysburg in July 2nd and suffered heavy casualty during the Pickett's charge on July 3rd. Armistead was captured again that day by the Union. he was imprisoned in Fort McHenry and was transferred to Fort Delaware prison camp on Oct 26, 1863. He was sent to Point Lookout Prison camp on an unknown date. On Nov 19th, 1864, he was diagnosed by the camp hospital of having typhoid fever. Due to poor hygiene condition and extremely cold weather he passed away a few days later on Nov 23rd.
