In 475, Jangsu launched a full-scale invasion from both land and sea against the now politically unstable kingdom of Baekje. Dorim was successful in gaining information about Baekje, and consequently Gaero was not at all prepared for the assault formulated by Jangsu. With momentum now in his favor, Jangsu then proceeded toward the capital and easily captured the city of Wiryeseong and slew Gaero. Soon after, Jangsu burned the capital to the ground, along with several other cities that he conquered from Baekje. Henceforth, Baekje had no choice but to move its capital to mountainous Ungjin (present-day Gongju), 80 miles to the south, which provided a natural protection for the devastated kingdom. The war gave Goguryeo more or less total control of the Han River valley, the region essential to commercial and military power in the Korean peninsula. Baekje had been a dominant power on the peninsula for hundreds of years thanks to its control of the region, but after losing the region to Goguryeo, Baekje also lost control of the peninsula.