How did cannonballs explode?

Do cannonballs really explode on impact?

No—they don’t. Despite what you might have seen in swashbuckling pirate films or dramatic war reenactments, real historical cannonballs rarely exploded on contact. In fact, most didn’t explode at all.

Solid iron cannonballs, the kind used to smash through ship hulls or fortifications, were inert lumps of metal. Their destructive power came from sheer momentum, not explosives. These were the workhorses of naval and field artillery for centuries, tearing through wood and flesh with brutal efficiency—but silently, without fireworks.

However, there were explosive projectiles, like shells and spherical case shot, but they operated very differently than Hollywood suggests. These hollow iron spheres were filled with gunpowder and fitted with a fuse, not a trigger mechanism. The fuse was lit before firing, designed to burn for a set time, ideally detonating the shell mid-air or just after landing. It was imprecise, dangerous, and certainly not activated by impact.

True percussion fuses, where a projectile explodes upon hitting something, weren’t developed until much later, during the 19th century, and even then, they were used on elongated shells, not round cannonballs. The idea of a cannonball striking a target and bursting into flames the moment it lands is more myth than reality.

So, the next time you watch a movie where a cannonball hits the deck and erupts in a fiery blast, remember: that’s cinematic flair, not history. Real warfare was loud, messy, and terrifying enough without Hollywood’s help.