The Howitzer, like artillery units in general, is used to effectively take out enemy buildings from a safe distance and to bring down a city's defenses, so Infantry and Cavalry units may capture it. The Howitzer outranges all defensive structures like Forts and Towers. It is also somewhat effective when attacking enemy artillery and slow-moving ships like Battleships. However, despite its ability to deal splash damage, it's pretty useless against other units or even crowds.