Chaos is a commonly used term for an error that can be used to benefit a player. The error, “There is chaos on the battlefield", is returned whenever a player attempts to launch a 41st attack on a city. Because the game has a 40 attack limit, any attempt to go over this will fail. This can be used both offensively, and defensively.
Using Chaos OffensivelyEdit
If you and a competitor are trying to get control over the same plot of land, it would be smart to send in a wave (or multiple waves) of Scholars, followed by any number of other waves of other slow forces, many people chose Ram. That way, your opponent is unable to send any attacks, and you have complete peace to destroy your target.
Using Chaos DefensivelyEdit
This is the main reason people use Chaos. If an ally of yours is getting attacked, and supplies are on the way, stalling is your best bet, and Chaos is essentially that. By spamming the city with Scouts, or recalling any one unit wave, you can block it from any actually harmful attacks by a competitor, until help arrives. Keep in mind that support and attacks are two completely different things, meaning that you can have a '41st' wave of supplies coming, while still keeping the city in chaos.