The Paixhans gun (French: Canon Paixhans, ) was the first naval gun designed to fire explosive shells. It was developed by the French general Henri-Joseph Paixhans in 1822–1823. The design furthered the evolution of naval artillery into the modern age. Its use presaged the end of wood as the preferred material in naval warships, and the rise of the ironclad. Background Explosive shells had long been in use in ground warfare (in howitzers and mortars) and on bomb vessels against stationary targets, but they were fired only at high angles and with relatively low velocities. The shells of that time were inherently dangerous to handle, and no method had been found to safely fire the explosive shells with the high power and flatter trajectory of a high-velocity gun. However, before the advent of radar and modern optical controlled firing, high trajectories were not practical for ship-to-ship combat. Such combat essentially required flat-trajectory guns in order to have a reasonable chance of hitting the target. Therefore, ship-to-ship combat had consisted for centuries of encounters between flat-trajectory cannons using inert cannonballs, which could inflict only local damage, even on wooden hulls. Mechanism Paixhans advocated using flat-trajectory shell guns against warships in 1822 in his Nouvelle force maritime et artillerie. Paixhans developed a delaying mechanism that, for the first time, allowed shells to be fired safely in high-powered flat-trajectory guns. The effect of explosive shells lodging into wooden hulls and then detonating was potentially devastating. Henri-Joseph Paixhans first demonstrated this in trials against the two-decker Pacificateur in 1824, in which he successfully broke up the ship. Two prototype Paixhans guns had been cast in 1823 and 1824 for this test. Paixhans reported the results in Experiences faites sur une arme nouvelle. The shells had a fuze that ignited automatically when the gun was fired; they lodged in the wooden hull of the target, and exploded a moment later: The first Paixhans guns for the French Navy were made in 1841. The barrel of the guns weighed about 10,000 lbs. (4.5 metric tons), and proved accurate to about two miles. In the 1840s, France, Britain, Russia, and the United States adopted the new naval guns. The effect of the guns in an operational context was first demonstrated during the actions at Veracruz in 1838, at Campeche in 1843, Eckernförde in 1849 during the Danish–Prussian War, and especially at the Battle of Sinop in 1853