The move from Chainmail based wargames to fullblown Dungeons & Dragons is often noted by game historians. Often it is described in terms of a conceptual revolution. But even taking that quantum leap for granted, many RPGs include some sort of wargame element. Some games pretty much demand mass combat resolution of some sort. Games set in the genre of giant fighty robots aren't really complete unless you can play out vast armies of mecha slugging it out, for instance. And Pendragon's abstract war rules are definitely needed for an rpg so narrowly focused on the exploits of cavalrymen.
Lately I've been thinking about the origins of the World of Greyhawk. Reading Gygax's words in early Dragon articles and such I get the distinct impression that initially he wasn't 'worldbuilding' in the sense the term is used today. That is to say, creating an artistically inspiring fantasy world was not his foremost goal. Instead, the World of Greyhawk developed initially as a fictional Europe-equivalent for Chainmail campaigns. I think you can still see artifacts of this era of Greyhawk in some of the placenames. I'd bet dollars to donuts that the Kingdom of Keoland got its name because it started life as the home country of Tom Keogh's troops. Similarly, what else could the Grand Duchy of Geoff be but the home country of a player named Geoffrey? The latter is obvious to me as I know for a fact that all people name Jeff are total egomaniacs.
So now I've got this idea in my head that maybe an authentic D&D campaign should run parallel to a wargame campaign using Chainmail or some other set of rules. Players who build castles and gain followers would immediately have something to do with those shiny new toys. Running through a few wargame sessions before starting the D&D game would also give some nice background that would be immediately accessible to the players. Why are you all at the tavern? Because the 23rd Goblin War just ended and you've decided you're not quite ready to go home. Why do you trust the cutthroats, wandering priests, and wizard's apprentices assembled around the table? Because they, too, held the line when the chips were down at the Battle of Felltree Pass. Why the heck are all these bandits and hobgoblins wandering the countryside? Because the war just ended last week and it was the kind of fiasco where nobody really won.
Then let the PCs wander around for almost a year of game time. Maybe they encounter some war refugees. Maybe have the villages they visit are burned to the ground. Maybe the party will parley for a change when they encounter some bandits and you say "They're flying the colors of Lord Remrik, who saved your unit's bacon at Umlo Hill. The hobgoblins destroyed his lands and sacked his castle, banditry is all he has left."
When the 24th Goblin War rolls around the experience will be much richer. The D&D sessions will give the wargame some really juicy context, while the wargaming gave texture to the RPG. Assuming your group likes both kinds of games, that's a win-win scenario.
AD&D Players Handbook part 10
3 hours ago