John T. Wilder was born in Hunter, New York, but began his career as an industrialist in Ohio and Indiana. At the outbreak of the United States Civil War, Wilder closed his foundry in Greensburg, Indiana and enlisted in the United States Army Indiana Infantry Regiment. Because of his leadership skills he was consistently promoted, eventually commanding the 17th Indiana Infantry Regiment as a Lieutenant Colonel. During the war he served in Virginia, Kentucky, Georgia, and Tennessee. Wilder was among the first officers to mount his troops and to supply them with Spencer Repeating Rifles, which they used to great effect in the Battle of Chickamauga in Georgia. Wilder and his troops would become known as "Wilder's Lightning Brigade." Wilder was promoted to the brevet rank of Brigadier General in 1864. After the war, Wilder and his family moved to Chattanooga, Tennessee, where he founded the Roane Iron Company and served briefly as postmaster and mayor.