What did the nobles do for Charlemagne in return?

In return for Charlemagne's support and leadership, the nobles provided military service, loyalty, and governance over the territories he conquered. They managed local administration, collected taxes, and maintained order in their regions, ensuring the stability of his vast empire. In exchange, they received land, titles, and protection, which reinforced their status and power within the Carolingian Empire. This reciprocal relationship helped Charlemagne consolidate his authority and expand his realm.