According to the kind of loading mechanism used, there are three types of rifles that are still used today by modern armies and civilians in hunting: bolt-action, semi-automatic, and assault rifle, which are well-known in the history of the 20th century warfare. The former is manually-operated through a bolt handle which opens and closes the bolt in the receiver, whereas the semi-automatic and assault rifles are automatically reloaded through the pressure exerted by the cartridge ignition gas, which drives backward the bolt carrier, through a piston or by direct impingement.
The first bolt-action rifles were the Dreyse needle gun and Chassepot, a Prussian and a French breech-loading, single-shot weapons respectively, used in the Austro-Prussian War and the Franco-Prussian War. These guns were further developed and improved during the second half of the 19th century and by the time World War I broke out in 1914 every industrialzied nation had already issued their armies with reliable, accurate, and powerful bolt-action rifles, such as the Lee-Enfield, the Mauser Gewehr 98. or the Lebel M1886, which would continue in service for many years after this armed conflict.
Introduced in 1936, the first massively produced semi-automatic rifle was the M1 Garand, which was in service with the US Army and Marine Corps for almost two decades, being the most efficient and dependable infantry weapon of World War II. If the United States of America was the first country in the world to equip its foot soldier with a semi-automatic rifle, it was also the first nation to issue its troops with an assault rifle, which was the BAR (Browning Automatic Rifle) M1918. Although it is not considered as such, technically it is an assault rifle, for it was fitted with a selective fire mechanism for both single-shot and fully automatic modes. However, the assault rifle was massively manufactured as standard issue infantry rifle during the post-war period. The most famous assault rifles in the last century, which became ideological symbols of the Cold War, were the AK-47 and the FN FAL rifles, in service with communist country armies and the free world armies respectively.
A Belgian infantry soldier armed with an FN FAL assault rifle