Broadly, a
simulation of military or politico-military action for entertainment, training or analytical purposes.
The use of wargaming as a tool for staff training and experiment dates back to the Kriegspielen run by the German general staff of the late 19th century, while US Navy Captain (later Admiral) Alfred T. Mahan was a forerunner of naval wargaming prior to the Spanish-American war. Games were generally 'neutrally' umpired (which inevitably led to many such exercises just serving to reinforce the conclusion desired by whoever was in charge) and took a variety of forms, with or without the use of models or other representations of the battles in question. Wargaming techniques have continued to be developed and used for these purposes up to the present day, with the invention of the computer coming in handy from its earliest days. (see Game Theory)
Wargaming for entertainment took two main forms in the pre-comuter era: games using miniatures - scale models and tin soldiers on a tabletop or floor with model terrain - and the simpler but less flexible board games. Miniatures gaming rode to some extent on the coat-tails of the hobbies of military modelling and to a lesser extent railway modelling (a handy source of scenery); in the UK it was popularised by a series of books by Donald Featherstone in the late 1960s and early 1970s. Levels of realism (leaving aside the general unpleasantness of war) were rather variable, since boring stuff like logistics and politics tended to get left out of the equation, and limited intelligence and communications problems were rather difficult to simulate. It is also easier to persuade plastic troops to fight to the last man than it is with real ones.
Boardgaming was largely spurred on by the board game publisher Avalon Hill and its offshoot SPI. It offered a way of taking a broader view than the necessarily tactical slant given by miniatures gaming, but for the average teenage anorak demanded a rather greater capital investment. From the late 1970s onwards the generally historical or contemporary slant of the games available started to drift towards swords and sorcery and space opera settings, popularised by the boom in role-playing games started by Dungeons and Dragons; miniatures gaming went much the same way.
The era after the introduction of home computers deliberately left blank for another putative noder.