Trinoda Necessitas, three species of contributions to which in Anglo-Saxon times all the lands of England, were subject—viz. bricg-bot, for keeping the bridges and highways in repair; burh-bot, for keeping the fortresses in repair; and fyrd, for maintaining the military and naval force.
Trinoda Necessitas
Chambers's Encyclopaedia, Volume 10: Swastika to Zyrianovsk and Index, p. 297
Source scan(s): p. 0316