The Collaborative International Dictionary of English v.0.48:

Besiege \Be*siege"\, v. t. [imp. & p. p. Besieged; p. pr. &
   vb. n. Besieging.] [OE. bisegen; pref. be- + segen to
   siege. See Siege.]
   To beset or surround with armed forces, for the purpose of
   compelling to surrender; to lay siege to; to beleaguer; to
   beset.
   [1913 Webster]

         Till Paris was besieged, famished, and lost. --Shak.
   [1913 Webster]

   Syn: To environ; hem in; invest; encompass.
        [1913 Webster]

WordNet (r) 3.0 (2006):

besieged
    adj 1: surrounded by hostile forces; "the besieged town"