During the Warring States Period, how did the State of Qin perish?

In 222 BC, Wang Ben, the general of the Qin Dynasty, led an army to annihilate the army of the Yan State in Liaodong, and captured the Yan State alive. On the way back to the Li Dynasty, he seized Wang Jia from the remnants of Zhao in Daibei (now Daixian County, Shanxi Province), and then took advantage of it to attack Qi State. King Jian of Qi quickly assembled troops on the western front to prepare for resistance. In 22 1 year BC, Qin Jun avoided the main force of the Qi army on the western front and went straight to Linzi (now Zibo, Shandong), the capital of the Qi State, from the north. With the Qin army under siege, Qi surrendered without a fight, and Qi perished.