| [[File:Heavy Cannon.jpg|250px]]|
The Heavy Cannon is a heavy artillery piece that is featured in Age of Empires III. It is a strong cannon unit that is built at the Factory (see Hidden Cost below) or shipped from the Home City for free.
The Heavy Cannon is the typical heavy artillery piece for the Spanish, Portuguese, Germans, Russians, Dutch and French. The Heavy Cannon is also available to these same civilizations from their Home City shipments (2 Heavy Cannon), most notably the Russians who can send a total of four cannons thanks to the Tsar Cannon card.
The Heavy Cannon's power and hit points are similar to the Great Bombard, but the rate of fire is slightly faster and it has no penalties versus Cavalry. The Heavy Cannon is effective against enemy infantry and artillery units, Spanish cannons using Unction are also effective versus Cavalry and other Artillery due to high damage and lack of significant penalties. Overall, a Heavy Cannon (1 on 1 and lacking Unction) would have a good chance to beat a Great Bombard with full health, though it would rely on the Heavy Cannon getting two shots off (12 seconds) before the Bombard began attacking the Heavy Cannon. This is realistically possible due to the Heavy Cannon's smaller penalty versus other artillery and its greater rate of fire. Other common factors such as battlefield confusion, varying levels of micromanagement skill and line of sight advantages allow this scenario to occur frequently. The population cost of this unit is 7.
Hidden Cost Edit
Training these units at a factory requires 115 seconds, 109.25 with Team Engineering School sent by a Chinese ally (for civilizations without Engineering School), 103.5 with Engineering School and finally 97.75 with both Home City Cards. The average resource gather rate of a Factory is 5.5 every second (before the building upgrade (+20%) and Home City Card, Market, etc upgrades). This means that Heavy Artillery from a Factory, while appearing to be free, will have a cost dependent upon how effective the factory gathers a needed resource. In many cases this cost can exceed the base value (700 resources) of the unit.