Allen was listed as living with his parents at 18 years old, born in Pickens County, and a farmer by trade.
During the American Civil War, Allen enlisted as a Private with Company 'C', Fourth Regimental South Carolina Cavalry on 16 Apr 1863. During his service, Allen was paid $24.40 in Jun 1863 for the use of his horse. Allen was listed as "present and on post duty 24 hours" between Sep - Oct 1863. He appeared on the muster roll of 29 Feb - 31 Aug 1864. On 8 May 1864, Allen arrived at White House, Virginia. On 28 May 1864, Allen was listed as "absent, captured" during the battle of Hawes Shop.
The battle at Hawes Shop was a fierce one for both sides. During the campaign from the Rapidan to the James, Major General P. H. Sheridan, commanding the cavalry corps, ordered a reconnaissance in the direction of Mechanicsville and sent out the 2nd division under Brigadier General David Gregg for the purpose.
Nearly a mile in advance of Hawes' shop, Gregg encountered the enemy's cavalry dismounted and behind a breastwork. He attacked this force, about 4,000 strong, but was repulsed repeatedly and would have had to withdraw but for the arrival of Brigadier General George C. Custer's brigade of the 1st division, four regiments of which were dismounted and charged in close column of attack in conjunction with an attack of Gregg's division.
The enemy was driven back, leaving his dead and wounded on the field. The casualties of the 2nd division were 256 killed and wounded. (source: The Union Army, Vol. 5, pg. 494).
Allen was captured by Union Forces. Sadly, his brother, Nathaniel, was killed during this conflict.
After his captured by Union forces, Allen was transferred to a prisoner of war camp at Point Lookout in Martinsville (St. Mary's County), Maryland. The camp rested on the very tip of Maryland, surrounded by water on three sides by the Chesapeake Bay and Potomac River. Point Lookout was well known as the largest prisoner of war camp during the Civil War.
Prison conditions were deplorable. Rations were below minimal, causing scurvy and malnutrition. Prisoners ate rats and raw fish. It's recorded that one hungry Rebel devoured a raw seagull that had been washed ashore. Soap skim and trash peelings were often eaten when found. Lice, disease, and chronic diarrhea often resulted in an infectious death. Prisoners were deprived of adequate clothing, and often had no shoes in winter or, only one blanket among sixteen or more housed in old, worn, torn, discarded union sibley tents. Even the Point's weather played havoc with the prisoners. Because of it's location, it's extremely cold with icy wind in the winter and a smoldering sun reflecting off the barren sand in summer was blinding. High water often flooded the tents in the camp area. The undrained marshes bred mosquitoes. Malaria, typhoid fever and smallpox was common. The brackish water supply was contaminated by unsanitary camp conditions. There was a deadline about 10' from the approximate 14' wooden parapet wall. Anyone caught crossing this line, even to peek through the fence, was shot. Prisoners were also randomly shot during the night as they slept, or if they called out from pain.
Provost Marshall Major Brady and Major General Benjamin (Beast) Butler would review the prison camp from time to time. Many times they galloped through the crowd of men, hitting them as they sped by. The sixty-gun Minnesota was within a short distance from the shore to guard the prisoners.
In all, over 50,000 men, both military and civilian, were held prisoner there. G.W. Jones, a private of Company 'H', Twenty-Fourth Virginia Cavalry, described his ominous entrance into the prison amidst "a pile of coffins for dead rebels".
Allen was only 21 years, 1 month, and 21 days old. Almost three months after Allen's death, his father filed a "Claim for Settlement" with the government on 14 Nov 1864.