"On the way to the coast, however, they fought what must be one of the
 most curious battles of all time.  They besieged a castle that was
 defended entirely by sheep.  The local inhabitants had driven their
 flocks into the disused fortress known Hosn al' Akrad ('citadel of the
 Kurds').  When the Crusaders attacked, the peasants rather craftily
 released a few of the animals and the Christians--predictably--went
 chasing off in pursuit.  This gave the locals a chance to slip away into
 the night, leaving their flocks behind them.  When the Crusaders resumed
 the siege, they couldn't understand why no one was fighting back.  They
 suspected it was yet another peasant ruse, whereas in fact it was the
 purely technical problem sheep have in mounting any sort of armed
 resistance."

 - from _Crusades_, by Terry Jones and Alan Ereira, c. 1995 Fegg
   Features Ltd and Alan Ereira.