Born on October 18, 1857, in Philippi, Virginia (now West Virginia),[1] Dayton attended the public schools, read law and received an Artium Baccalaureus degree from West Virginia University in 1878, then received a Master of Arts degree in 1880 from the same institution.[1] He was admitted to the bar and entered private practice in Philippi from 1878 to 1879,[1] with his father Spencer Dayton.[2] He was prosecutor for Upshur County, West Virginia from 1879 to 1884.[1] He was prosecutor for Barbour County, West Virginia from 1884 to 1888.[1] He resumed private practice in West Virginia from 1886 to 1895.[1]