 However, in 1256, he dispatched a Bahri-led expedition to Egypt, but no battle occurred when Aybak met an-Nasir Yusuf's army.Aybak was assassinated on 10 April 1257, possibly on the orders of Shajar al-Durr, who was assassinated a week later.Their deaths left a relative power vacuum in Egypt, with Aybak's teenage son, al-Mansur Ali, as heir to the sultanate.