The .45-70 cartridge is a centerfire rifle cartridge that was developed in the late 19th century for use in the Springfield Model 1873 trapdoor rifle, which was the standard service rifle of the United States Army at the time.

The .45-70 cartridge was designed to replace the earlier .50-70 cartridge, which had been in use since the early 1860s. The new cartridge had a shorter case with a larger diameter, allowing for the use of a heavier bullet. The original load used a 405-grain lead bullet over 70 grains of black powder, giving it a muzzle velocity of around 1,350 feet per second.

The .45-70 cartridge was first adopted by the U.S. military in 1873, and it remained in service until it was replaced by the .30-40 Krag cartridge in the late 1890s. During its service life, the .45-70 cartridge was used in a variety of rifles and carbines, including the Springfield Model 1873, the Springfield Model 1884, and the Winchester Model 1886.

In addition to its military use, the .45-70 cartridge was also popular with civilian hunters and shooters. It was used for hunting large game, such as bison and bear, and for target shooting at long range.

Today, the .45-70 cartridge remains in use by hunters and shooters, and it is still popular for long-range shooting and hunting of large game. Modern versions of the cartridge are loaded with smokeless powder and come in a range of bullet weights and types, making it a versatile cartridge for a variety of applications.