From the following site http://ancienthistory.about.com/cs/troyilium/a/taleoftroy_3.htm

Crafty Odysseus devised a plan that ultimately doomed the Trojans. Sending all the Greek ships away or into hiding, it appeared to the Trojans that the Greeks had given up. The great wooden gift the Greeks left before the walls of the city of Troy appeared to be an offering to Athena -- a peace offering. The jubilant Trojans dragged the monstrous, wheeled, wooden horse into their city to celebrate the end of the ten years of fighting.
But beware of Greeks bearing gifts!