Trojan Horse

Horses were a major trade product in Troy. Because of this the Trojans favored the horse because of the vast amounts of wealth it brought, and uses it had. Therefore the Trojan Horse would have been a much favored metaphor, and an obvious much more exciting story than anything else. The Trojan Horse is thought to perhaps have been an earthquake, because Poseidon was not only god of the sea and horses, but of the sea as well. Another explanation can be the Greeks perhaps disguising themselves as the cavalry unit that Hector led, or a siege engine that the ancient military would often name after animals.

http://www.stanford.edu/~plomio/history.html