Mark -- John L. Allen originally enlisted in Co. K, 16th Arkansas Infantry, at Elm Springs, Arkansas, on February 11, 1862. He was left behind, sick, at Van Buren when the regiment marched north to fight at Pea Ridge, and never rejoined the regiment. He was eventually dropped from the rolls when the regiment was transferred east of the Mississippi River.

He subsequently enlisted in Co. F, 27th Arkansas Infantry, at Locust Grove, Arkansas, on May 21, 1862. He was detailed to the newly-formed Brown's Arkansas Battery ("Newton Artillery") on August 4, 1862. This battery was organized entirely with details from various regiments in and around Batesville. He was ordered to report back to his regiment per Special Orders, No. 23, District of Arkansas, April 11, 1863. He was admitted to General Hospital, Shreveport, Louisiana, on April 10, 1865, due to intermittent fever, and returned to duty on April 17, 1865. He was paroled at Camp Allen, Shreveport, Louisiana, on June 8, 1865. His parole stated that his residence was Locust Grove, Arkansas.