Born in Mercer County, Kentucky, in October 18, 1830. He studied medicine at Rush Medical College and built a large practice in Iconium, Iowa. In 1859, he married Mary A.C. Kemper. Vermilion served as a captain in the Union Army during the Civil War. He was commissioned on October 4, 1862, to command Company "F" of the 36th Infantry Regiment of Iowa Volunteers and continued that assignment until his discharge on August 24, 1865. He was promoted to the rank of major shortly before the end of the war. After the Civil War, Vermilion was elected state senator (1869-1872) from Appanoose County to the Thirteenth General Assembly of Iowa, which met in Des Moines. His law practice included matters of contracts, collections, estates, litigation and property transaction. During the 1870s and 1880s, he served as the local attorney for the Chicago, Rock Island and Pacific Railroad in issues of right of way, contracts and litigation growing out of the building of railroads.