Paul La Farge at The Believer:
D&D gets its appetite for rules from wargames, which have been around for thousands of years. The modern war game began in the late eighteenth century, when a certain Helwig, the Master of Pages to the German Duke of Brunswick, invented something called “War Chess”: instead of rooks and knights and pawns it featured cavalry, artillery and infantry; instead of castling it had rules for entrenchment and pontoons. The Prussians adapted Helwig’s game to train their officers; the French learned the value of wargames the hard way in 1870. In 1913, when the Prussians were again rattling their sabers, the British writer H. G. Wells came up with a game called Little Wars, which was played on a tabletop, with miniature lead or tin soldiers. Then, in 1958, a fellow named Charles Roberts founded the Avalon Hill game company, and published a board game based on the battle of Gettysburg. Gettysburg and its successors were wildly popular; all over America, college students and other maladjusted types began to recreate, in their dorms and basements and family rooms, the great battles of history.
more here.