charge of the base, engaged Yang. Gao achieved initial success against Yang, and became arrogant, feasting on the battlefield. When Dou heard this, he, in surprise, stated, "The Duke of Donghai has not yet defeated the enemy but has become arrogant. A disaster will happen soon. After the Sui victory, they will attack here as well, and I am afraid we will not be spared." Several days later, Yang defeated Gao and killed him on the battlefield. He then attacked Dou, whose army collapsed. Dou fled, and Yang, not believing that he would be able to accomplish much, withdrew. Dou returned and gathered the remnants of Gao's army, and he publicly observed a mourning period for Gao. After his army had recovered somewhat, he claimed the title of general, and he began to capture territory around him. It was said that the rebels had hated Sui officials so much that they largely slaughtered Sui officials whenever they could find those officials. However, Dou did not do so, and treated Sui officials and scholars kindly, and therefore at times Sui officials would even surrender their cities to him. He soon had more than 100,000 soldiers under his command. Nominal submission to Li Mi and Yang Tong In spring 617, Dou claimed the title of Prince of Changle and also changed the era name that his followers used, from Emperor Yang's Daye () to Dingchou (), thus subtly signifying an official break from Sui. In fall 617, at Emperor Yang's orders, the general Xue Shixiong (), who was in charged of defending Zhuo Commandery, led his 30,000 men south, intending to attack Li Mi—then generally recognized as the strongest rebel leader. As Xue went through Hejian Commandery (河間, roughly modern Cangzhou, Hebei), near Dou's holdings, Dou's army became fearful and fled. Xue thus took no further precautions, believing Dou to pose no further threat. Dou instead planned a surprise attack, leading 280 of his best soldiers personally as the forward assault force at night while having the rest of his men trail. He made an agreement with them—that if they reached Xue's camp at night, they would make a surprise attack, but if it was already the day by the time that they arrived, they would surrender. The sun rose when Dou was almost at Xue's camp, and Dou, fearful that he would be crushed by Xue, discussed with his men whether