The main debate here is whether Charlemagne's wars were motivated primarily by religious beliefs and objectives or alternative purposes. A variety of motives can be identified and these include political/dynastic, personal as well as religious concerns. Much of the reign was taken up by wars and it may be significant that, for the most part, Charlemagne's opponents were pagan, Muslim or in dispute with the Papacy. In assessing the importance of religious motivation, it can be argued that in the wars in Germany, Spain and Italy in the first ten years of the reign, there were few signs of religious mission. Motives were entirely or very largely, political. In the later period however, religious beliefs seemed to play an important role with military campaigns involving forcible conversion and baptisms, missionary activity and the foundation of monasteries in conquered territories.
Tribute and plunder was the prized income of the Franks from warfare. The treasure of pagan temples was also a preferred object of plunder. Hywel Williams for example, strongly supports this motive on page 75, whereupon he describes the substantial amount of gold and silver contained within the Irminsul, a sacred shrine. On first sight, this leads us to suggest that Charlemagne's invasion of Saxony was purely motivated by personal reasons, for plunder and booty. There are flaws within this judgment however, as the true value of the Irminsul can be perceived in many different ways. Williams for instance, proceeds to suggests that the attack on the Irminsul had an underlying religious significance. After all, this is the first recorded evidence of the Franks devising a pre-planned attack on a Saxon religious centre.
The king kept fighting men in the palace without fixed positions or incomes, who lived from gifts of food and clothing, gold and silver, horses and arms. Rewards were thus expected for the professional warrior and it was the only way by which Charlemagne could convince them into enlisting into his army.