A broadside is the side of a ship; the battery of cannon on one side of a warship; or their simultaneous (or near simultaneous) fire in naval warfare.
In older naval warfare
Broadsides were quite different during older naval warfare, in the age of sail
. An 18th century man of war
like the HMS Victory
had cannons that were only accurate at short range. The penetrating power of naval guns was mediocre; which meant that the thick hull of a well-built wooden ship could only be pierced at short ranges. These wooden ships sailed closer and closer towards each other until cannon fire would be effective. Each tried to be the first to fire a broadside, often giving one side a decisive headstart in the battle when it crippled the other ship.
As a measurement
Additionally, the term broadside is a measurement of a vessel's maximum simultaneous fire power
which can be delivered upon a single target, due to the fact that this concentration is usually obtained by firing a broadside. This is calculated by multiplying the shell weight of the ship's main armament shells times the number of barrels that can be brought to bear. If some turrets are incapable of firing to either side of the vessel, only the maximum number of barrels which can fire to one side or the other are counted. For example, the American Iowa
carry a main armament of nine 16-inch main guns in turrets which can all be trained to a single broadside. Each 16-inch shell weighs 2,700 pounds, which when multiplied by nine (the total number of barrels in all three turrets) equals a total of 24,300 pounds (11,022 kg). Thus, an Iowa
-class battleship has a broadside of 12 short tons (11.0 tonnes), the weight of shells that she can theoretically land on a target in a single firing.
See list of broadsides of major World War II ships for a comparison.