During the 1898 war with Spain, the Mauser M1893 used by the Spanish Army gained a deadly reputation, particularly from the Battle of San Juan Hill, where 750 Spanish regulars significantly delayed the advance of 15,000 US troops armed with outclassed Springfield Krag–Jørgensen bolt-action rifles and older single-shot Springfield model 1873 trapdoor rifles.

Likewise, earlier in the day, a Spanish force of 540 regulars armed with the same Mauser rifles, under Spanish general Vara Del Rey, held off General Henry Ware Lawton's Second Division of 6,653 American soldiers and an independent brigade of 1,800 men for ten hours in the nearby town of El Caney, keeping that division from assisting in the attack on the San Juan Heights.

The US military licensed many of the Mauser Company's and other German patents, including the spitzer bullet, later modified into the .30-06 Springfield.

[7] The two main problems usually cited with the Krag were its slow-to-load magazine and its inability to handle higher chamber pressures for high-velocity rounds.

The United States Army attempted to introduce a higher-velocity cartridge in 1899 for the existing Krags, but its single locking lug on the bolt could not withstand the extra chamber pressure.

Though a stripper-clip or charger loading modification to the Krag was designed, it was clear to Army authorities that a new rifle was required.

After the U.S. military's experience with the Mauser rifle in the 1898 Spanish–American War, authorities decided to adopt a stronger Mauser-derived bolt-action design equipped with a charger- or stripper clip-loaded box magazine.

In 1882, the bolt action Remington Lee rifle design of 1879, with its newly invented detachable box magazine, was purchased in limited numbers by the U.S. Navy.

Several hundred M1882 Lee Navy models (M1882 Remington-Lee) were also subjected to trials by the U.S. Army during the 1880s, though the rifle was not formally adopted.

The Navy adopted the M1885, and later different style Lee M1895 (a 6 mm straight pull bolt), which saw service in the Boxer Rebellion.

This new design was accepted, type classified and officially adopted as the United States Rifle, Caliber .30, Model 1903 and entered production in 1903.

The Warner & Swasey Model 1913 musket sight continued to see service after the Pancho Villa Expedition and during World War I but was eventually deemed inadequate and was removed from the US Army's inventory by the 1920s.

[14] By the time of US entry into World War I, 843,239 M1903 rifles had been produced at Springfield Armory and Rock Island Arsenal.

The Mark I has a cut on the left hand side of the receiver meant to act as an ejection port for the Pedersen device, a modified sear and cutoff to operate the Pedersen device; a specialized insert that replaced the bolt and allowed the user to fire .30 caliber pistol cartridges semi-automatically from a 40-round detachable magazine.

[20] However, during the late 1930s, it became apparent that, with the development of mortars, high-angle artillery, and the .50 caliber M2 Browning machine gun, the need for extreme long-range, rifle-caliber machine-gun fire was decreasing.

Costa Rica troops were equipped with Springfields during the Coto War and some rifles were captured by the opposing Panamanians.

The two-piece firing pin-striker also proved to be no improvement over the original one-piece Mauser design, and was a cause of numerous ordnance repairs, along with occasional reports of jammed magazine followers.

[24] World War II saw new production of the Springfield at private manufacturers such as the Remington Arms and Smith-Corona Typewriter companies.

[24] Other modifications included a new stamped cartridge follower; the rounded edges of the new design largely alleviated the "fourth-round jam" complaints of the earlier machined part.

[29] Original production rifles at Remington and Smith-Corona had a dark gray-black finish similar to the bluing of late World War I.

Cleaning was sometimes lax when fighting in the jungle on various Pacific islands, and the higher moisture levels compounded the corrosive action of the residue.

[30] The M1903 and the M1903A3 rifles were used in combat alongside the M1 Garand by the US military during World War II and saw extensive use and action in the hands of US troops in Europe, North Africa, and the Pacific.

[32] The U.S. Army Rangers were also a major user of the M1903 and the M1903A3 during World War II with the Springfield being preferred over the M1 Garand for certain commando missions.

[citation needed] According to Bruce Canfield's U.S. Infantry Weapons of WW II, final variants of the M1903 (the A3 and A4) were delivered in February 1944.

[24][34][35] The USMC and the US Army would eventually switch to a large 8x scope that spanned the length of the rifle designed by John Unertl.

In August 1943, the Free French Forces of General Charles de Gaulle were re-equipped by the United States, primarily with M1903 Springfield and M1917 Enfield rifles.

[citation needed] This new rifle was simply equipped with a very long and powerful Unertl 7.8x (as compared to the M73B1 2.5X telescopic sights issued with the army's M1903A4) variant type scope.

Marine Corps armorers continued to rebuild some M1903 sniper rifles as late as the early stages of U.S. involvement in the Vietnam War.

[clarification needed] In 1977, the U.S. Army located a rather large cache of unissued M1903A3 rifles which were demilitarized and then issued to JROTC units as a replacement for their previously issued M1 Garand and M14 rifles, which were then returned to Army custody due to concerns about potential break-ins at high school JROTC armories.

For safety reasons, the JROTC M1903s are made permanently unable to fire by plugging the barrel with a steel rod, or having it filled with lead, soldering the bolt and welding the magazine cutoff switch in the "on" position.