His deputy commander, Chen Tang claimed that Zhizhi was planning to build up a great empire and proposed a pre-emptive attack.
It marched west on both sides of the Tarim Basin, reunited near Kashgar and moved across Kangju territory reaching the western shore of Lake Balkhash.
At this point a party of several thousand Kangju cavalrymen, returning from a raid on Wusun, stumbled onto the rear of the Chinese army, attacked it, and made off with a large quantity of food and weapons.
Chen Tang sent his Hu troops back and defeated the Kangju, killing 460 of them and freeing 470 Wusun captives.
The following spring Gan Yanshou and Chen Tang arrived at Chang'an and presented Emperor Yuan of Han with Zhizhi's severed head.