In 512 (the 13th year of the reign of King Jijeung), Yisabu became the lord and governor of Aseulla (present-day Gangneung, Gangwon-do) and established a plan to merge Usanguk (present-day Ulleungdo and Dokdo Islands). As the people of Usanguk were known to be foolish and ferocious, he thought that it would be difficult to subjugate them by force and thus had no choice but to come up with a cunning stratagem. He ordered his men to carve many wooden lions and to load them on to his warships. When his ships reached the beach of Usanguk, he threatened the island's inhabitants, saying, "If you do not surrender, we'll release these wild beasts and they will trample you all to death." Terrified, the locals surrendered on the spot. - Samguk sagi (History of the Three Kingdoms) Vol. 4

Yisabu became the Minister of Defense in 541 (the 2nd year of the reign of King Jinheung), wielded considerable influence until 562, and contributed greatly to expanding Silla's control in all directions.

Usanguk was a mini-state composed of present-day Ulleungdo and other adjacent islets. As for Usanguk's territory, Mangi Yoram (an inventory of every military base and encampment in Korea) states that both Ulleungdo and Usando (referring to "Matsushima", the ancient Japanese name for present-day Dokdo) belong to Usanguk, clearly indicating that Dokdo was a part of Usanguk's territory.

According to Sukjong Sillok (The Veritable Record of the Reign of King Sukjong), An Yongbok clashed with some Japanese fishermen from the Oya Family while fishing and farming along with about ten other men, including Park Eodun, whereupon they were forcefully taken to Oki Island of Japan in 1693 (the 19th year of the reign of King Sukjong). The chief of Oki Island took An Yongbok and his company to Governor-General Hokishu at Tottori Castle. There, An Yongbok stressed that Ulleungdo Island belonged to Joseon and asked the governor-general to prohibit Japanese fishermen from fishing near the island.

The governor-general reported the matter to Edo Bakufu and persuaded its Shogun to write a letter to the effect that "Ulleungdo is not Japan's territory" and hand it to An Yongbok, and to release the captives so that they could return home to Joseon via Nagasaki and Tsushima. However, upon their arrival in Tsushima, the head of Tsushima took the letter written by the Shogun of Edo Bakufu from them and then handed the men over to Dongnae-bu, Busan, Joseon.

Sometime later, when An Yongbok went to Ulleungdo to gather marine products in the spring of 1696 (the 22nd year of the reign of King Sukjong), he saw some Japanese boats fishing there. He drove them away and then sailed to Tottori Domain to protest about the Japanese fishing near Ulleungdo, which was Joseon's territory. While there, he again asked the governor-general to prohibit Japanese fishing near Ulleungdo and Dokdo Islands once and for all, pointing out that the islands belonged to Joseon.

The governor-general said, "The islands belong to your country. Accordingly, we will impose a heavy punishment on any of our people who invade Joseon's territory in the future. As regards this matter, we will draw up a state letter and designate an interpreter," according to a decision made by Edo Bakufu. Thus, Edo Bakufu of Japan issued an order prohibiting Japanese ships from sailing to Ulleungdo Island, which was the eventual outcome of An Yongbok's reminder that the islands were Joseon's territory. Furthermore, in 1877, the Meiji Government of Japan re-confirmed that both Ulleungdo and Dokdo Islands were parts of Joseon's territory and had nothing to do with Japan.

Despite their government's prohibition of Japanese ships sailing to Ulleungdo Island following the protest of An Yongbok, a group of Japanese set about the unauthorized felling of trees in Ulleungdo Island in 1881, and a local government official reported their illegal behavior. The governor of Gangwon-do reported the matter to the central government, which appointed Lee Gyuwon as an inspector charged with looking into the situation in Ulleungdo Island. During his stay from April 30 to May 11, 1882, Lee Gyuwon drew up his Daily Inspection Journal, in which he recorded a list of the marine products that were gathered or caught there, as well as the fertility of the land and the local topography in great detail. In addition, he confirmed that the Japanese lumberjacks had set up a signpost and were taking away the trees they had felled in Ulleungdo Island.

Upon receiving the report from Lee Gyuwon, the Joseon government sent a letter of protest to Japan and initiated a project for the redevelopment of Ulleungdo Island. Following the relocation of 54 people of 16 households from the mainland in April 1883 as part of the project, the number of residents in Ulleungdo Island gradually increased. In October 1900, the Korean Empire issued Imperial Decree No. 41, which upgraded Ulleungdo Island to an independent do, an administrative unit, and placed a county headman in control of Ulleungdo and Dokdo Islands.

This shows that Lee Gyuwon's report led the central government to adopt a new policy for the management of Ulleungdo Island, bringing to an end the 400-year-long policy of allowing no people to live on the island and simply maintaining it as a remote part of the country's territory.

Hong Sunchil was born in Ulleungdo Island in January 1929. His grandfather, Hong Jaehyeon, moved from Gangneung to Ulleungdo Island in 1883, under the government's project to redevelop the island, and spent the rest of his life there. Hong Sunchil grew up understanding that Dokdo was attached to Ulleungdo Island.

With the outbreak of the Korean War in 1950, Hong joined the Army and was one of the troops that advanced up to Cheongjin, Hamgyeongbuk-do. He was wounded near Wonsan during the retreat of the UN Forces after the Chinese entered the war, and retired from the military as a master gunnery sergeant in July 1952.

Immediately after his retirement, he happened to see a signpost inscribed with the Japanese words "Takeshima, Oki-gun, Shimane-ken" in a corner of the ground at the Ulleungdo Police Station. In that instant, something in his mind told him to do something useful to defend Dokdo.

He organized the Dokdo Volunteer Forces composed of local young army veterans and bought weapons with his own money. Following their first landing on Dokdo in April 1953, the Dokdo Volunteer Forces engaged in a skirmish with patrol boats of the Japanese Coast Guard on several occasions.

Hong Sunchil strived to protect Dokdo as a part of the country's territory in the face of numerous hardships without any outside aid. His heroic acts played a decisive role in helping the country with its effective occupation of Dokdo. In recognition of his meritorious deeds, he was posthumously awarded the Defense Meritorious Service Medal and the Order of National Security Merit in 1966 and 1996, respectively. An article entitled 'Volunteer Dokdo Guard' written by him was included in the Unknown Soldier's Medal, a collection of memoranda of life submitted by those who rendered distinguished service to the country. Hong's memoir titled 'This Land Is Ours' was published in 1997.