and northern Hamgyong armies under the command of Yi Yong at Songjin. A Korean cavalry division took advantage of the open field at Songjin, and pushed the Japanese forces into a grain storehouse. There the Japanese barricaded themselves with bales of rice, and successfully repelled a formation charge from the Korean forces with their arquebuses. While the Koreans planned to renew the battle in the morning, Katō Kiyomasa ambushed them at night; the Second Division completely surrounded the Korean forces with the exception of an opening leading to a swamp. Those that fled were trapped and slaughtered in the swamp. Koreans who fled gave alarm to the other garrisons, allowing the Japanese troops to easily capture Kilju County, Myongchon County, and Kyongsong County. The Second Division then turned inland through Puryong County toward Hoeryong, where two Korean princes had taken refuge. On August 30, 1592, the Second Division entered into Hoeryong where Katō Kiyomasa received the Korean princes and the provincial governor Yu Yong-rip, these having already been captured by the local inhabitants. Shortly afterward, a Korean warrior band handed over the head of an anonymous Korean general, plus General Han Kuk-ham, tied up in ropes. Katō Kiyomasa then decided to attack a nearby Jurchen castle across the Tumen River in Manchuria to test his troops against the "barbarians", as the Koreans called the Jurchens (Orangkae in Korean and Orangai, both derived from the Mongol term Uriankhai "forest barbarian"). Kato's army of 8,000 was joined by 3,000 Koreans at Hamgyong Province, because the Jurchens periodically raided across the border. Soon the combined force sacked the castle, and camped near the border; after the Koreans left for home, the Japanese troops suffered a retaliatory assault from the Jurchens. Katō Kiyomasa retreated with his forces to avoid heavy losses. Because of this invasion, rising Jurchen leader Nurhaci offered military assistance to the Joseon and Ming in the war. However, the offer was refused by both countries, particularly Joseon, saying that it would be disgraceful to accept assistance from the "Barbarians" to the north. The Second Division continued east, capturing the fortresses of Jangseong, Onsong, Kyongwon, and Kyonghung Counties, and finally arrived at Sosupo on the estuary of the Tumen River. There the Japanese rested on the beach, and watched a nearby volcanic island on the horizon that they mistook as Mount Fuji. After the tour, the Japanese continued their previous efforts to