Jacob Widaman was born in Pennsylvania around 1833. By the early 1860s, he was living in Indiana and working as a tobacconist. He enlisted in the Union army on April 19, 1861, and mustered in as a captain in the 8th Indiana Infantry six days later. The regiment spent the next three months in western Virginia serving under General George B. McClellan, and the men took part in the Battle of Rich Mountain that July. He mustered out on August 6, 1861, but he reenlisted a month later and mustered in as a 1st lieutenant in Company G of the 8th Indiana Infantry on September 5. He was promoted to captain on March 5, 1863, and to major on May 1, 1865. He mustered out in Savannah, Georgia, on August 28, 1865. He died sometime after 1865.