The Saxon Wars (772–804) of Frankish king Charlemagne against the Saxons under Widukind were described by Jim Bradbury (2004) as 'in essence a frontier struggle and a religious war against pagans – devil-worshippers according to Einhard.' He noted that Charlemagne ordered the destruction of the Irminsul, an object sacred to the Saxons. Per Ullidtz (2010) stated that previous Frankish–Saxon conflicts spanning almost a century 'had been mostly a border war', 'but under Charles it changed character': because of 'Charles' idea of unity, of a king over all German tribes, and of universal Christianity in all of his kingdom, it changed into a mission from heaven.' Similarly, a successful Carolingian campaign against the Pannonian Avars in the 790s led to their forced conversion to Christianity. The earlier Merovingian conquests of Thuringia, Allemannia and Bavaria had also resulted in their Christianisation by 555, although the Frisians resisted with similar determinacy as the Saxons during the Frisian–Frankish wars (7th and 8th century), with both tribes killing several Christian missionaries in defence of their Germanic paganism, to the horror of Christian hagiographers. Crusades The Crusades are a prime example of wars whose religious elements have been extensively debated for centuries, with some groups of people in some periods emphasising, restoring or overstating the religious aspects, and other groups of people in some periods denying, nuancing or downplaying the religious aspects of the Crusades in favour of other factors. Winkler Prins/Encarta (2002) concluded: "The traditional explanation for the Crusades (a religious enthusiasm that found an outlet in a Holy War) has also retained its value in modern historical scholarship, keeping in mind the fact that it has been pointed out that a complex set of socio-economic and political factors allowed this enthusiasm to manifest itself." The Crusades against Muslim expansion in the 11th century were recognized as a "holy war" or a bellum sacrum by later writers in the 17th century. The early modern wars against the Ottoman Empire were seen as a seamless continuation of this conflict by contemporaries. Reconquista Jim Bradbury (2004) noted that the belligerents in the Reconquista were not all equally motivated by religion, and that a distinction should be made between 'secular rulers' on the one hand, and on the other hand Christian military orders which came from elsewhere (including the three main orders of Knights Templar, Knights Hospitaller and Teutonic Knights), or were established inside Iberia (such as those