Allen was born on February 12, 1843 in Lebanon, New York. During the American Civil War, he served with the 22nd Wisconsin Volunteer Infantry Regiment of the Union Army. He would take part in the Battle of Thompson's Station, Battle of Resaca, Battle of Kennesaw Mountain, Battle of Peachtree Creek and Sherman's March to the Sea. On September 4, 1867, Allen married Delia A. Sherman. He died on May 5, 1908.