Henri-Joseph Paixhans was a French artillery officer of the beginning of the 19th century.

In 1823, he invented the Paixhans guns, which were the first naval guns to combine explosive shells and a flat trajectory, thereby triggering the demise of wooden ships, and the iron hull revolution in boat building.

Explosive shells had long been in use in ground warfare (in howitzers and mortars), but they were only fired at high angles and with relatively low velocities. Shells are inherently dangerous to handle, and no solution had been found yet to combine the explosive character of the shells with the high-power and high velocity of a flat-trajectory gun.

High-trajectories are not practical however for marine combat. Naval combat essentially requires flat-trajectory guns in order to have some odds of hitting the target. Therefore naval warfare had consisted for centuries in encounters between flat-trajectory cannons using inert cannonballs, which a wooden boat could rather easily absorb.

Paixhans developed a delaying mecanism which, for the first time, allowed shells to be fired safely in high-powered flat-trajectory guns. The effect of explosive shells hitting wooden hulls and setting them aflame was devastating.

In the late 1830s, France, England, and the United States had adopted the new naval guns. Wooden boats became so vulnerable that the only possible response could come with the introduction of the iron-hulled warship. The first of them was the French La Gloire, soon followed by the HMS Warrior.