What is... Kriegspiel?

Kriegsspiel, from the German word for wargame, was a war game first created in 1812 by von Reiswitz and was named Instructions for the Representation of Tactical Maneuvers under the guise of a wargame. It is considered one of the very first proper war games. Prior attempts had simply been iterations of chess or some other game without much change, the creator of Kriegsspiel set out to create a new experience entirely. For exmaple he decided instead of being based on a rigid square grid, the game would feature an area of terrain. Reiswitz' system for simulating war was initially based around a specially designed table which he created for his King Friedrich Wilhelm III before creating something that then established many of the classic war game features seen today.
After its initial development, this particular style of wargaming became very popular among the Prussian Army officer corps. After numerous successful Prussian campaigns in the late 1800s, Kriegsspiel became more widely adopted by many militaries.