Combined Arms (Civ6)/Civilopedia

Since the earliest age, able military commanders had integrated formations of infantry, archers and whatever passed for cavalry in battle with more or less success. But it wasn't until the campaigns of Gustavus Adolphus who fielded 3-pounder cannon in his infantry regiments and attached teams of musketeers to his cavalry units that the concept showed its true worth. As the century progressed, several European nations combined musketeers, light infantry, dragoon and horse artillery into unified brigades. Napoleon revolutionized tactics by employing fast-moving advance detachments composed of light cavalry, light infantry and horse artillery in his Grande Armée.
Despite the descent into trench warfare on the Western Front, the First World War brought two new weapons to the forefront – the tank and the airplane. In the following years before the next big brouhaha, various military thinkers proposed new combined-arms systems for the "all-arms battles” they envisioned. These would include such as close artillery support, air support and tanks and infantry in mutual support during an attack. One of those whose ideas drew some attention was a German officer named Erwin Rommel, whose book 'Gefechts-Aufgaben für Zug and Kompanie' was published in 1934. The successful blitzkrieg in the West and East was carried out with fast-moving armored formations, supported by motorized infantry, self-propelled guns and specialized ground-support aircraft.
After the successes against the Germans, the superpowers adopted the combined-arms approach as doctrine (never mind the nuclear missiles poised to rain down). The U.S. Marine Corps, for instance, formalized the concept of the independent Marine Air-Ground Task Force in 1963. The Vietnam War and the Soviet-Afghan War brought air-mobile forces and “special forces” to the field, allowing for quick-strike offensives in a range of terrain not suited to conventional combined-arms operations. The Gulf Wars finally gave the world a chance to see the new combined-arms theories put into practice, with impressive results.