introduced to the battlefield. Firearms are qualitatively different from earlier weapons because they release energy from combustible propellants such as gunpowder, rather than from a counter-weight or spring. This energy is released very rapidly and can be replicated without much effort by the user. Therefore even early firearms such as the arquebus were much more powerful than human-powered weapons. Firearms became increasingly important and effective during the 16th century to 19th century, with progressive improvements in ignition mechanisms followed by revolutionary changes in ammunition handling and propellant. During the American Civil War new applications of firearms including the machine gun and ironclad warship emerged that would still be recognizable and useful military weapons today, particularly in limited conflicts. In the 19th century warship propulsion changed from sail power to fossil fuel-powered steam engines. Since the mid-18th century North American French-Indian war through the beginning of the 20th century, human-powered weapons were reduced from the primary weaponry of the battlefield yielding to gunpowder-based weaponry. Sometimes referred to as the "Age of Rifles", this period was characterized by the development of firearms for infantry and cannons for support, as well as the beginnings of mechanized weapons such as the machine gun. Of particular note, howitzers were able to destroy masonry fortresses and other fortifications, and this single invention caused a revolution in military affairs, establishing tactics and doctrine that are still in use today. World War I An important feature of industrial age warfare was technological escalation – innovations were rapidly matched through replication or countered by another innovation. World War I marked the entry of fully industrialized warfare as well as weapons of mass destruction (e.g., chemical and biological weapons), and new weapons were developed quickly to meet wartime needs. The technological escalation during World War I was profound, including the wide introduction of aircraft into warfare, and naval warfare with the introduction of aircraft carriers. Above all, it promised to the military commanders the independence from the horse and the resurgence in maneuver warfare through extensive use of motor vehicles. The changes that these military technologies underwent were evolutionary, but defined the development for the rest of the century. Interwar This period of innovation in weapon design continued in the inter-war period (between WWI and WWII) with continuous evolution of weapon systems by all major industrial powers. The major armament firms were Schneider-Creusot (based in France), Škoda Works (Czechoslovakia), and