There were a large number of cities in Greece, each of which needed to defend itself from its neighbours. Greek cities did not have armies of full-time soldiers, instead all the men in the city had to fight when required with their own armour and weapons. The Greek poet Homer described how Greek and Trojan heroes fought each other in chariots, and their servants and the ordinary soldiers fought on foot. Later on, Greeks fought in a strict battle line, standing in rows. They wore heavy armour, which protected them very well when they fought as a group. They were called 'hoplites' after the shields they carried (called a 'hoplon').