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howitzer is a class of gun with many different variants you need to be more specific. but the max range of a M777 howitzer is 30.1 km (rap assisted).
A large cannon fired at a high angle.
See the related link to the M198 155mm towed howitzer and the M109A self propelled howitzer.
mortar, howitzer
howitzers were made in the early 17th century
Yes, "Howitzer" is generally capitalized. It is a proper noun and refers to a specific type of artillery cannon.