The invasion of Egypt is sometimes explained by Zenobia's desire to secure an alternative trade route to the Euphrates, which was cut because of the war with Persia. This theory ignores the fact that the Euphrates route was only partially disrupted, and overlooks Zenobia's ambition. The date of the campaign is uncertain; Zosimus placed it after the Battle of Naissus and before Claudius' death, which sets it in the summer of 270. Watson, emphasizing the works of Zonaras and Syncellus and dismissing Zosimus' account, places the invasion in October 270 (after Claudius' death). According to Watson, the occupation of Egypt was an opportunistic move by Zenobia (who was encouraged by the news of Claudius' death in August). The appearance of the Palmyrenes on Egypt's eastern frontier would have contributed to unrest in the province, whose society was fractured; Zenobia had supporters and opponents among local Egyptians.