Although the term infantry dates from the 15th century, the foot troops of the previous eras in history who fought with a variety of weapons before the introduction of the firearms are also referred to as infantry. During the Ancient and Middle Ages infantry were often categorized by the types of weapons and armour they used, such as heavy infantry and light infantry. Generally, light infantry acted as skirmishers, scouts, and as a screening force for the more heavily armed and armored heavy infantry, the latter of which often made up the bulk of many historic armies. With the introduction of firearms, line infantry would come to dominate the makeup of most armies, their name reflective of both their formations and fighting style. During this time period, light infantry often served as elite marksmen while retaining their scouting and skirmishing role. This era would also see the founding of many naval infantry or marine units. With the introduction of advanced modes of transportation such as motor vehicles, armored fighting vehicles, and aircraft, new tactics and infantry designations were developed, such as motorized, mechanized, and airborne infantry. Specialized units, such as mountain infantry were also created. Light infantry, in the modern sense, has come to represent generalist professional infantry units whom, despite their non-specialized nature, often play an important role in combined arms warfare. The word infantry was borrowed into other Romance languages from the Latin infantem, a "foot soldier" who served in groups composed of those soldiers who were too-inexperienced or too low in rank for membership to the cavalry. As a meaning for an organised type of combat troops, the word dates to 1579 in the French infantrie and Spanish infanteria. However, in military history it has become a common English term to apply to troops from earlier historical periods. With the notable exception of the Mongol Empire, infantry has represented the largest component in most armies of the past, as well as the present. While the specific weapons have varied, the common factor is that these soldiers have relied on their feet for tactical movements, but since the introduction of the rail and motor transport have been operationally transported behind the front-lines, and have made use of strategic airlift with the introduction of aircraft into warfare. During Ancient history, infantry was essentially an armed mob, fighting in loosely organized opposing lines, under the vocal direction of individual commanders in the immediate vicinity of the troops' hearing range. However, the benefits of uniform, equipment, weaponry and, above all, training led to the development of formations able to carry out pre-arranged tactical maneuvers in the heat of battle. Since that time, infantry organization has focused on finding a balance between heavily armed formations that emphasise firepower and ability to withstand direct assaults, and more lightly armed but also more mobile units able to manoeuvre around the battlefield faster, to exploit tactical opportunities. Mobility, armament, and protection have been the three competing primary factors that complement and compete in the balanced approach to development of infantry doctrine throughout history. (en)
Although the term infantry dates from the 15th century, the foot troops of the previous eras in history who fought with a variety of weapons before the introduction of the firearms are also referred to as infantry. During the Ancient and Middle Ages infantry were often categorized by the types of weapons and armour they used, such as heavy infantry and light infantry. Generally, light infantry acted as skirmishers, scouts, and as a screening force for the more heavily armed and armored heavy infantry, the latter of which often made up the bulk of many historic armies. (en)