linguistic:translation, structural:reformatting
Replacement by the rifle

The musket was a smoothbore firearm and lacked rifling grooves that would have spun the bullet in such a way as to increase its accuracy. The last contact with the musket barrel gives the ball a spin around an axis at right angles to the direction of flight. The aerodynamics result in the ball veering off in a random direction from the aiming point. The practice of rifling, putting grooves in the barrel of a weapon, causing the projectile to spin on the same axis as the line of flight, prevented this veering off from the aiming point. Rifles already existed in Europe by the late 15th century, but they were primarily used as sporting weapons and had little presence in warfare. The problem with rifles was the tendency for powder fouling to accumulate in the rifling, making the piece more difficult to load with each shot. Eventually, the weapon could not be loaded until the bore was wiped clean. For this reason, smoothbore muskets remained the primary firearm of most armies until the mid-19th century. It was not until 1611 that rifles started seeing some limited usage in warfare by Denmark. Around 1750, rifles began to be used by skirmishers of Frederick the Great, recruited in 1744 from a Jäger unit of game-keepers and foresters, but the rifle's slow rate of fire still restricted their usage.

The invention of the Minié ball in 1849 solved both major problems of muzzle-loading rifles. Rifled muskets of the mid-19th century, like the Springfield Model 1861 which dealt heavy casualties at the Battle of Four Lakes, were significantly more accurate, with the ability to hit a man-sized target at a distance of 500 yards (460 m) or more. The smoothbore musket generally allowed no more than 300 yards (270 m) with any accuracy.

The Crimean War (1853–1856) saw the first widespread use of the rifled musket for the common infantryman and by the time of the American Civil War (1861–1865) most infantry were equipped with the rifled musket. These were far more accurate than smoothbore muskets and had a far longer range, while preserving the musket's comparatively faster reloading rate. Their use led to a decline in the use of massed attacking formations, as these formations were too vulnerable to the accurate, long-range fire a rifle could produce. In particular, attacking troops were within range of the defenders for a longer period of time, and the defenders could also fire at them more quickly than before. As a result, while 18th-century attackers would only be within range of the defenders' weapons for the time it would take to fire a few shots, late-19th-century attackers might suffer dozens of volleys before they drew close to the defenders, with correspondingly high casualty rates. However, the use of massed attacks on fortified positions were not immediately replaced with new tactics, and as a result, major wars of the late 19th century and early 20th century tended to produce very high casualty figures.