 Emperor Yang's main forces put Goguryeo's key northern city Liaodong (遼東, in modern Liaoyang, Liaoning) under siege (although he was ultimately unable to capture it), but sent Yuwen with a branch army to head deep south, across the Yalu River, heading directly toward the Goguryeo capital Pyongyang.However, on the way, his army ran out of food supplies and was forced to withdraw, and as it did, Goguryeo forces gave chase and crushed him.When Emperor Yang retreated as well, he put Yuwen under imprisonment, but still remembering his relationship with Yuwen, did not execute him, but reduced him to commoner rank.