Bethesda, Tennessee is an unincorporated community in rural southeastern Williamson County, Tennessee. In the spring of 1861 the Webb Guards company of the Tennessee infantry was raised from the towns of Triune, College Grove, Peytonsville and Bethesda. The company was then organized as Company D of the 20th Tennessee Volunteer …Bethesda, Tennessee is an unincorporated community in rural southeastern Williamson County, Tennessee. In the spring of 1861 the Webb Guards company of the Tennessee infantry was raised from the towns of Triune, College Grove, Peytonsville and Bethesda. The company was then organized as Company D of the 20th Tennessee Volunteer Infantry.