[2] Goguryeo consolidated its power and began to threaten the Chinese commanderies, under the nominal control of Wei.
In 242, Dongcheon attacked a Chinese fortress near the mouth of the Yalu River leading to the Goguryeo–Wei War; in 244, Wei invaded Goguryeo and sacked Hwando.
General Mil U (밀우; 密友) and Yu Okgu (유옥구; 劉屋句) also repulsed the Wei forces.
[8] This passage was not paralleled in Chinese records, and Hiroshi Ikeuchi points out its errors: the author of this passage in Samguk sagi regarded the region of South Okjeo and Lelang as identical, while in fact they are on opposite sides of the peninsula;[9] also, the references to the "Eastern Department" for Yu Yu and Mil U are anachronistic, since Goguryeo did not divide the country into departments until the middle of the Goguryeo dynasty — that is, after Dongcheon's reign.
It is well accepted that this invasion indicated a sudden inflow of refugees from Goguryeo into a bordering area with Silla.