Stories of the Japanese 01380 [Muromachi/Yoshinori Period] The Yuki War: Siege Warfare

On July 29, 1440 (the 12th year of Eikyo), a shogunate army of 100,000 surrounded Yuki Castle and launched a simultaneous attack. However, despite being a flatland castle, Yuki Castle was impregnable and would not easily fall. This was because the castle had a natural moat utilizing the river flowing around its outer perimeter, and Ujitomo had spent time renovating it specifically for a siege.
Furthermore, Ujitomo had deliberately dispersed his force of about 20,000 soldiers, stationing Ujiyuki Noda at Koga Castle and Ujitane Yabe at Sekiyado Castle (Noda City, Chiba Prefecture). From the perspective of the shogunate army, there was a risk of being sniped from the rear by Koga and Sekiyado Castles while attacking Yuki Castle, which was another reason the general offensive was not progressing well.
Even in September, Yuki Castle did not fall, and the impatient Shogun Yoshinori issued an unexpected order.
"Surround them with a large army and starve them out."
This was a cautious strategy for the short-tempered Yoshinori.
On October 20, Iezumi Iamatsu (1409–1494) of the shogunate side sent a secret letter to Ujiyoshi Yamakawa, who was inside the castle, inviting him to defect.
"If you give me Yuki Castle, I will defect."
He said this and escaped the castle, but he was treated like a prisoner by the shogunate side and mocked by those around him.
Nevertheless, this betrayal by Ujiyoshi was a painful blow to the Yuki side. Morale dropped, and food supplies began to dwindle.
Deciding that enough was enough, Yoshinori ordered a general attack in November. However, the morale of the shogunate army on the ground was low, and they were reluctant to move. While this was happening, on January 1, 1441 (the 13th year of Eikyo), the Shimosa Yuki clan led by Ujitomo launched a sortie from the castle. They had likely run out of food and were gambling on a do-or-die battle. They fought for a full day, but the outcome remained undecided.
Around the same time, information arrived that Yoshiaki Daikakuji, who had been plotting a rebellion in league with Mochiuji, had fled to Hyuga. At the time, the position of Shugo of Hyuga and Satsuma had been passed from Hisatoyo Shimazu to his son, Tadakuni (1403–1470). Acting on the shogunate's orders, Tadakuni raided the Kushima Eitoku-ji Temple (Kushima City, Miyazaki Prefecture), where Yoshiaki was hiding, on March 13, 1441 (the 1st year of Kakitsu), and forced him to commit suicide.
While the matter of Yoshiaki was quickly resolved, the situation in the Yuki War showed no signs of movement.
On April 15, Kiyokata Yamauchi-Uesugi, the commander of the local shogunate army, declared:
"It is a disgrace that we have not been able to take the castle for several months, even though half of Japan's military strength is assembled here. We will launch a general attack tomorrow."
"Half of Japan's military strength" might be an exaggeration, but it is true that they were struggling to attack despite having a large army, and it was a loss of face. The attack was finally about to begin.