In the first half of the Twentieth Century, the new 'horseless' mobility contributed massively to the Affairs of Man. After the Bicycle Craze of the 1890, the motorcycle and automobile gave people freedom to move around at will, lifted rural isolation and made urbanization in the suburbs possible. The same happened when new machines conquered the skies; the Zeppelins and the airplanes connecting continents. And at the base of this mobility revolution was a new invention: the Internal Combustion Engine (IC-Engine). Nineteenth Century tinkerers and thinkers had used the steam engines to experiment with the Power of Combustion in a controlled way. Using new liquid propellants replacing steam, they created step by step a new type engine running on petrol; the IC-Engine. A development trajectory in which many contributed and that culminated around the 1860s when Etienne Lenoir brought those ideas together in one concept. His work inspired others such as Nicolaus Otto who created the four-stroke engine. And when Rudolf Diesel added his version running on heavy oils, the IC-Engine was ready to conquer the world. It started when early bicycles and quadricycles became powered by single-cylinder IC-Engines. By 1885 German engine designs powered the Petroleum Reitwagen (Gottlieb Daimler) and Patent Motorwagen (Carl Benz). These vehicles sparked massive interest in Europe among carriage and bicycle makers, who started improving engine design and vehicle design. Their open automobiles soon hit the country roads and racing tracks. The Second Power Revolution exploded in a tsunami of industrial activity by the turn of the century. Even more when it crossed the Atlantic Ocean, where it was heralded by the bicycle and carriage makers. And it came to obsess the young farmer's boy Henri Ford, who-after some experimenting, racing and business conflicts-constructed his 'famers car' Model T. This was the dawn of the new era that brought mobility to the masses.Additionally, the IC-engine came to power the air-vehicles by the turn of the century. The more after the Wright Brothers made the flyer manoeuvrable, the multi-winged, petrol-powered airplanes developed rapidly. Their flight demonstrations in Europe, excited the masses. The military used the fixed-wing planes as a new tool for reconnaissance and air combat in warfare during the First World War, but civil aviation took over during the following inter-war period. The more when Charles Lindberg crossed the Atlantic in a solo-flight. Next to the multi-engine seaplanes, the airships (aka Zeppelin) travelled the airways between continents. Air carriers offered their regular scheduled services to an ever-increasing number of passengers.And at the core of all this novelty was the IC-engine embarking on a continuous road of improvement into the multi-cylinder power engines. Its application in mobility was complemented by other uses. The IC-engine became the prime mover for powering factories, electricity generation, but also for propelling (war)ships and locomotives. The tractor and harvester changed agricultural practises, increasing food production. It created new manufacturing industries and their employment, stimulated economies and influenced the outcome of wars. The IC-engine powered the Third Industrial Revolution, influencing the Affairs of Man fundamentally during the Era of Mechanization.