Source : Webster's Revised Unabridged Dictionary (1913)

Trench \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.] --Bacon.

   {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.