Japanese invasion of Silla and Balhae prevented it.

 Japan, which has constantly threatened the Korean Peninsula. Among Japan's numerous invasion of the Korean Peninsula, there was another invasion plan that had not been known. In 762, 90 years after the unification of the three kingdoms of Silla. Japan is about to start a war on the Korean Peninsula. Why did Japan try to attack Silla? Japan's plans to invade Silla, including the manufacture of more than 500 warships and Itoseong Fortress, which was built for the final showdown as a military base, have been carried out over the years. Balhae held the decisive role of the Silla invasion plan. Even as Balhae, it was in isolation due to the friendly relationship between Silla and the party, and it was difficult to reject Japan's request for cooperation in order to withstand the Silla and the party's checks. However, Balhae refused to invade Silla by Japan! Why did Balhae refuse to cooperate with Japan? How could peace in East Asia last? This week's History Special. "Discovery of History"! In "Japanese invasion of Silla, Balhae prevented it," we trace the hidden history and the secrets of Japanese invasion of Silla. ◆ Details: 1. Itoseong Fortress, a military base built in Fukuoka targeting Silla beyond Japan's Silla Invasion Operation Plan over many years, an order from 759 to build 500 ships within three years, and Japan, which allowed boys to learn Silla. There was only a foreign war in which hundreds of ships were built at once. At the time when there was no external invasion, Japan planned to attack Silla first, and preparations were underway to invade Silla. 2. The history of Japan's defeat as an ally of Baekje in 663 to the Japanese at the time, who believed the legend of Empress Shingong's conquest of Samhan in AD200 was disgraceful. And in the continued diplomatic tension with Silla, Japan decided to invade Silla. 3. The protagonist of the Silla invasion, an ambitious figure hidden behind the invasion plan, was Nakamaro Fujiwara, the absolute power at the time when even the emperor controlled it. Nakamaro Fujiwara devoted his efforts to the invasion of Silla to transfer criticism and resistance toward him. Nakamaro asks Balhae of the Eastern Kingdom to cooperate to beat Silla, which had a strong power. At that time, Japan and Balhae were in military alliance and were scheduled to advance to Silla as soon as Balhae's participation was decided. 4. Silla was already preparing for the Japanese invasion. After noticing Japan's invasion plan, Silla began to build a large-scale Mobalsanseong Fortress to protect Gyeongju. In addition, elite units using Silla's representative weapon, Noh, were deployed. When Japan was planning to conquer Silla, Silla was even undergoing military reform to mobilize all its military power. 5. The Silla invasion plan was canceled. Balhae eventually rejects the Shilla Cooperation Plan. Just in the 750s, exchanges between Silla and Balhae began. It was the gateway to Tanhang Port at the mutual contact center on the border that symbolized the time when the two countries changed from tension and confrontation to friendship. Balhae and Silla of the Eastern Kingdom began to recognize each other as Korean people. Eventually, Balhae turned down Japan's request.