He attempted to strengthen royal control of the aristocracy, by selecting officials from his own Buyeo clan, at the expense of the powerful Hae and Jin clans. In 469, he ordered a surprise attack in which the city of Cheongmongnyeon (청목령, 靑木嶺; near modern
Kaesong) was retaken from
Goguryeo. In 472, he sent an embassy bearing tribute to
Northern Wei requesting support against Goguryeo's attacks. However, these advances were rebuffed by the Wei court, which tried to avoid war with Goguryeo which had greater military power at the time, while fighting against
Southern Dynasties. In the early 470s, according to the
Samguk sagi, King
Jangsu of Goguryeo sent a
Buddhist monk named
Dorim, who was actually a Goguryeo agent. Dorim used Gaero's passion for the game of
baduk to ingratiate himself, and persuade the king to neglect the country's defense in favor of public works. ==Fall of the capital==