An Etymological Dictionary of the German Language/herrschen
herrschen, vb., from MidHG. hersen, hêrsen, OHG. hêrisôn, ‘to rule, reign,’ but also hêrrisôn even in OHG., from its association with hêrro, ‘lord’ (for ModHG. sch after r from an older s, comp. Hirsch, Kirsche). The origin of the meaning ‘to rule’ cannot be explained from the posit. hehr, OHG. hêr, ‘august, exalted, venerable, glad,’ but from the originally compar. hêrro, ‘lord.’ Thus OHG. hêrisôn, ‘to be lord and master, dominari,’ is related to hêrro, hêriro, ‘lord,’ as Goth. *hairiza (compar.) is to *hairisôn, vb.