Apennines and plundered Tuscia, but historians are not in full agreement as to whether this took place under his guidance and if this constituted anything more than raiding. According to Herwig Wolfram, it was probably only in 578–579 that Tuscany was conquered, but Jörg Jarnut and others believe this began in some form under Alboin, although it was not completed by the time of his death. Alboin's problems in maintaining control over his people worsened during the siege of Ticinum. The nature of the Lombard monarchy made it difficult for a ruler to exert the same degree of authority over his subjects as had been exercised by Theodoric over his Goths, and the structure of the army gave great authority to the military commanders or duces, who led each band (fara) of warriors. Additionally, the difficulties encountered by Alboin in building a solid political entity resulted from a lack of imperial legitimacy, as unlike the Ostrogoths, they had not entered Italy as foederati but as enemies of the Empire. The king's disintegrating authority over his army was also manifested in the invasion of Frankish Burgundy which from 569 or 570 was subject to yearly raids on a major scale. The Lombard attacks were ultimately repelled following Mummolus' victory at Embrun. These attacks had lasting political consequences, souring the previously cordial Lombard-Frankish relations and opening the door to an alliance between the Empire and the Franks against the Lombards, a coalition agreed to by Guntram in about 571. Alboin is generally thought not to have been behind this invasion, but an alternative interpretation of the transalpine raids presented by Gian Piero Bognetti is that Alboin may actually have been involved in the offensive on Guntram as part of an alliance with the Frankish king of Austrasia, Sigebert I. This view is met with scepticism by scholars such as Chris Wickham. The weakening of royal authority may also have resulted in the conquest of much of southern Italy by the Lombards, in which modern scholars believe Alboin played no role at all, probably taking place in 570 or 571 under the auspices of individual warlords. However it is far from certain that the Lombard takeover occurred during those years, as very little is known of Faroald and Zotto's respective rises to power in Spoletium (Spoleto) and Beneventum (Benevento). Assassination Earliest narratives Ticinum eventually fell to the Lombards in either May or June