A Battleship
An animation showing the main cannons in red and the secondary cannons in blue
HMS Dreadnought.
is a very large warship that has very large guns (measured in inches, and usually 11 inches in bore diameter). They are effective against ground units and other ships, though they do not usually have major anti-air capabilities. The most well-known battleship of all time was the HMS Dreadnought, of which construction was completed in 1906.