Jacob G. Frick became one of the early responders to President Abraham Lincoln's call for volunteers to help preserve his nation's union following the April 1861 fall of Fort Sumter to Confederate States Army. On September 23 of that year, at the age of 36, he enrolled for Civil War military service in Pottsville, Pennsylvania, and officially mustered in there that same day with the field and staff officers' corps of the 96th Pennsylvania Infantry. Commissioned as a lieutenant colonel, he served as his regiment's second in command,"Frick, Jacob G. (F&S - 96 I)", in "Civil War Veterans' Card File, 1861-1866". Harrisburg, Pennsylvania: Pennsylvania State Archives. and participated with his regiment in the Seven Days Battles from June 25—July 1, 1862, including the battles of Gaines's Mill (June 27), Glendale (June 30) and Malvern Hill (July 1).Bates, Samuel P. History of Pennsylvania Volunteers, 1861-5; Prepared in Compliance with Acts of the Legislature, Vol. III: "Ninety-Sixth Regiment", pp. 382-385, 390. Harrisburg, Pennsylvania: B. Singerly, State Printer, 1870.
