Hirelings

AD&D combat works best as a tactical skirmish game. This is hard to execute when every player only controls one character, so for this reason I think the early editions of D&D implemented retainers or henchmen and hirelings. However, I never understood henchmen as written. It seemed needlessly complicated to acquire and employ them, ordering them around added extra steps to every action, and in the strictest case the DM is supposed to run them, making it extra work on top of everything else. In the sense of using them as replacement characters for the players, I never understood why you couldn't just reroll a new character when your main one died, and a level 1 PC who would ostensibly need henchmen as backup is not allowed to recruit them as written, as they do not have enough fame to attract any followers. So its safe to say that I never used henchmen as written in AD&D.

Instead I use the hirelings list and allow players to employ mercenary soldiers as level 0 or level 1 fighters. They come with their own arms and equipment, and require the monthly cost as well as a split of treasure, and generally I let the players run the hirelings unless they wanted to do something exceptionally dangerous, which is when I call for a morale roll. The OD&D rules for retainers is much more usable, and much less complicated for handling their loyalty, morale, and general use.  I still cap the number of hirelings in the dungeon to the PC's charisma score - otherwise players will march whole armies down into the dungeon for a clean sweep.

Using this method transforms AD&D into a more tactical game, and away from the traditional RPG. Its advantage is that it makes combat more interesting and less instantly lethal, and it forces players to care about characters beyond their own, but the downside is that it takes away from the pure roleplaying experience and many players do not want to run multiple characters at once in this fashion.

One thing I had noticed, though, is that players love subjugating and turning enemy NPCs into their service. Goblins, especially, are prey to players who like to threaten them within an inch of their life and then force them to become minions. Honestly, I love it. I'd prefer it if players kept turning enemy NPCs into their henchmen. The caveat, of course, is that when the PC dies, the monster henchmen all desert.