The assumption of imperial titles by Zenobia signaled a usurpation: independence from, and open rebellion against, Aurelian. The timeline of events and why Zenobia declared herself empress is vague. In the second half of 271, Aurelian marched to the East, but was delayed by the Goths in the Balkans; this may have alarmed the queen, driving her to claim the imperial title. Zenobia also probably understood the inevitability of open conflict with Aurelian, and decided that feigning subordination would be useless; her assumption of the imperial title was used to rally soldiers to her cause. Aurelian's campaign seems to have been the main reason for the Palmyrene imperial declaration and the removal of his portrait from its coins.