Trench, v. i.
  1. To encroach; to intrench.
     Does it not seem as if for a creature to challenge to itself a boundless attribute, were to trench upon the prerogative of the divine nature?   --I. Taylor.
  2. To have direction; to aim or tend. [R.]
  To trench at, to make trenches against; to approach by trenches, as a town in besieging it. [Obs.]
  Like powerful armies, trenching at a town
  By slow and silent, but resistless, sap.   --Young.