Centuries ago, perhaps a gunner accustomed to firing his cannon became captivated with the idea of getting a second bang—not from his weapon but from the projectile at the target-end of its trajectory. Whatever its genesis, the weapon developed to achieve this goal was the mortar, and the only way devised to get the “second bang” was to use a fused projectile. The firing process was very hazardous and dependent on the experience and skill of the gunner to elevate the weapon, estimate the right amount of propelling charge for the range at hand, trim a fuse to the right length to have it explode on target, and then light the fuse before firing.
So many variables were involved that the mortar really was only good against the likes of massive land targets—stationary fortresses and castles. Warships needed guns capable of greater accuracy with which to fight other ships, with relatively flat trajectories so that they could be aimed more precisely at a target, but for centuries only high-trajectory mortars and howitzers fired exploding projectiles. By the early 19th century, navies were taking mortars to sea for shore bombardment in specially designed ships called bombs.