in the spring of 1448. The two armies met in Tarnab, where Ala al-Dawla was defeated, forcing him to withdraw to Abul-Qasim Babur in Astarabad. Mashhad was occupied by Ulugh Beg's forces, while Abdal-Latif conquered Herat. With this failure, Ala al-Dawla lost much support among his followers and never recovered his former pre-eminence. Even his grandmother Gawhar Shad appears to have doubted him, taking refuge instead with his brother Sultan Muhammad in Isfahan, bringing with her many of her relatives, nobles and a large number of troops. Conflict with his brothers By February 1449, Abul-Qasim Babur had gained control of Herat, having earlier inflicted a defeat on Ulugh Beg. Though Ala al-Dawla was still with him at this point, Abul-Qasim Babur was now undoubtedly the more prominent of the two. In spite of this, Ala al-Dawla still remained a threat due to his popularity among the population of Khorasan as well as his receiving their grandmother's continued favour. Abul-Qasim Babur therefore opted to imprison him alongside his son Ibrahim. However, Ala al-Dawla soon escaped, fleeing first to Ghur and then to Sistan. When his brother continued to pursue him, he retreated to Yazd, then held by Sultan Muhammad. Ala al-Dawla, alongside Gawhar Shad, encouraged Sultan Muhammad to march on Herat, which resulted in the defeat of Abul-Qasim Babur's forces and the capture of the city. Like his brother, Sultan Muhammad was concerned by Ala al-Dawla's continued support in the region and sent him away to Kabul to act as governor. However, by 1451 Ala al-Dawla had gained the support of the Arlat tribe, with whom he had marriage ties, allowing him to make another attempt for the throne. Whilst Sultan Muhammad was absent fighting their brother, Ala al-Dawla took control of Herat with the aid of the city's population. Sultan Muhammad, then facing an insurgency amongst his nobles, was unable to counteract this, instead being forced to devote resources to reestablishing his control over his central territories. However, Abul-Qasim Babur used this opportunity to attempt to retake Herat himself. On his approach Ala al-Dawla retreated to Balkh, though even in his absence it required a long siege by Abul-Qasim Babur to gain the city's surrender. In June of that year, Ala al-Dawla made a bid to capture Samarqand from Abdallah Mirza, who had taken the city following the deaths of Ulugh Beg and Abdal-Latif. Ala al-Dawla seized the cities of