I found a cheap copy of 1992 TSR's HR2 Charlemagne's Paladins. The historical reference is a better appellation than campaign sourcebook, there is one scenario included, but the campaign heavy lifting is left to the dungeonmaster.
The 95 pages plus color maps are articulated into chapters:
- A survey of carolingian history
- Character design
- The setting
- Equipment and treasure
- The tale of Charlemagne and his Paladins
- Adventures on the saxon frontier (Scenario)
The proper settings chapters are 1, 2, 4, and 6. The other chapters contain mostly differences with the vanilla AD&D 2nd Edition dungeonverse.
The suggested reading section closing chapter 2 points at non-fiction and fiction works. As expected, Orlando Furioso, Three Hearts and Three Lions, and the Osprey series on Charlemagne are not forgotten.
The settings assumes three possible play modes: Historical, Legendary, or Fantasy. For example, if playing Historical, the only available classes are Fighter, Cleric, and Thief. Playing a Paladin assumes Legendary or Fantastical.
They recommend that player characters be nobles or companions of nobles since they are the only ones to have the freedom and resources to travel, but suggestions of less noble characters are given anyway.
The NA (not applicable) delta approach goes for equipment as well, where the AD&D equipment list gets chopped down, no full plate or plate mail, no lanterns, etc. Clerics have list of allowed spells (moderated by mode, historical, legendary or fantasy) and restriction on spell effects. Wizards are discouraged, especially in historical mode, and have a list of prohibited spells.
The Adventures on the Saxon Frontier scenario is interesting. It railroads heavily at the beginning but it feels justified. The player characters are retainers to a lord and have to follow the lord. The dungeon master is expected to entertain the players and induce them to perform horsemanship feats. As the party just travelled from Northern Italy all the way to their home near modern Koblenz, let's tire the horses a last time with a final race to the gate of the manor. And tomorrow morning, it's boar hunt time, no time to rest.
It's railroady, but it plays its role, warming up the carolingian setting for the players. You're part of a motorcycle gang and count Brego is the boss. There is even less freedom outside of the gang.
I am pleasantly surprised by this HR2 book. You blur the AD&D tied parts and you get a "pre-medieval" setting that can deliver a lot. It might be worth adding it to a base of Wolves of God for a cross-channel dark age Europe, with some enlightenment powered by Alcuin of York. I like the the pivot between empire and feudalism, the sparsely populated Europe, prone to heresies and paganism, and still open to teutonic fantasy.
It's available as a PDF on Drivethru.