The Collaborative International Dictionary of English v.0.48:

Retreat \Re*treat"\, v. i. [imp. & p. p. Retreated; p. pr. &
   vb. n. Retreating.]
   To make a retreat; to retire from any position or place; to
   withdraw; as, the defeated army retreated from the field.
   [1913 Webster]

         The rapid currents drive
         Towards the retreating sea their furious tide.
                                                  --Milton.
   [1913 Webster]