A pitched battle or set-piece battle is a battle in which opposing forces each anticipate the setting of the battle, and each chooses to commit to it. Either side may have the option to disengage before the battle starts or shortly thereafter. A pitched battle is not a chance encounter such as a meeting engagement, or where one side is forced to fight at a time not of its choosing such as happens in a siege or an ambush. Pitched battles are usually carefully planned to maximize one's strengths against an opponent's weaknesses and use a full range of deceptions, feints, and other manoeuvres. They are also planned to take advantage of terrain favourable to one's force. Forces strong in cavalry, for example, will not select swamp, forest, or mountain terrain for the planned struggle. For example, Carthaginian General Hannibal selected relatively flat ground near the village of Cannae for his great confrontation with the Romans, not the rocky terrain of the high Apennines. Likewise, Zulu Commander Shaka avoided forested areas or swamps, in favour of rolling grassland, where the encircling horns of the Zulu Impi could manoeuvre to effect. Pitched battles continued to evolve throughout history as armies implemented new technology and tactics.