Used in Naval warfare tactics, The Broadside was a fighting ships ability to selectively or simultaneously fire it's cannon at an opposing vessel. Most Ships-of-The Line were built to feature 3 or 4 decks of cannon (Gun Decks), of various poundage. Warships were built quite sturdy and were many times reinforced (by cross planking). This was a standard form of protection for the ships hull. A single cannon ball little but structure damage (and easily repaired). By increasing the amount of shells and concentrating them at a specific point, the likelihood of increased and severe damage was done. Often, successive decks would fire (one after the other). The Broadside tactic was most effective at "danger close" distances of less than 100 yards. Often, warships would close in to each other and batter away until they achieved a victory (or withdrawal). As weapons technology advanced (as did ship building), the need for Broadside firing (in the classical sense) - ceased to be used.