John Allen was born in 1847 in Albemarle County, Virginia. Allen's life began in slavery, but Dr. Charles Everett manumitted him in 1848. After his manumission, Allen went to live in a free settlement in Mercer, Pennsylvania, called Pandenarium. He lived near George Washington Lewis, another former Everett slave, and the two served together in the same regiment during the Civil War. Allen spent his youth in New Brighton, Pennsylvania, before joining the Union army at the age of 17. He enlisted in Company A of the 127th USCT Infantry Regiment as a substitute for iron manufacturer George C. Reis. He mustered into service in Philadelphia on August 23, 1864. 

Allen enlisted for one year and participated in many pivotal military engagements, from the siege of Petersburg to the pursuit of Robert E. Lee to Appomattox. His unit witnessed Lee's surrender on April 9, 1865. Eventually, the unit was transferred to Texas, where it moved along the Rio Grande. Allen's unit held an impressive military career for the better part of a year, although he himself was absent sick from January to March at an unspecified General Hospital. His unit mustered out in Brazos Santiago, Texas, on September 8, 1865, and Allen left the army with the rank of private.

Allen married his wife Jane Allen shortly after the war. By 1870, they were living in Liberty, Pennsylvania, with an infant son named Richard. Allen never applied for a pension, and the family disappeared from the historical record after 1870.

Documents: 

The Liberator Article on Pandenarium Slaves