The siege of Kamakura (30 June-4 July 1333) was the final major battle of the Genko War (1331-33) and saw the army of Nitta Yoshisada capture the capital of the Kamakura Shogunate after a five-day long battle. The last Hojo ruler of Japan committed suicide at the end of the siege, and the Kamakura Shogunate died with him.
Nitta Yoshisada decided to join the Imperial cause when he was summoned to join the Bakufu forces besieging Chihaya. He arranged to receive an Imperial Mandate to attack the Hojo, feigned illness and returned to his home. He then began to raise an army, and in June 1333 openly went into revolt. He raised his banner on the 8th day of the 5th month (20 June 1333) at the shrine at Ikushina and began a successful march south towards Kamakura.
After an inconclusive battle at Kotesashi (23 June 1333) he won a significant victory a little further south at Kumegawa (24 June 1333). The Bakufu reinforced their army, and when Yoshisada attacked again on 27 June he was repulsed (battle of Bubaigawara, 27-28 June 1333). At the end of the first day of the battle the Bakufu failed to press their advantage. That night Yoshisada received reinforcements, and on the next morning he surprised the Bakufu forces in their camp, winning a descsive victory. The survivors of the defeat retreated back to Kamakura, where they prepared to defend the city.
Kamakura was built in a very defensible position. The city was surrounded by mountains, and could only be reached along a number of fortified mountain passes or by sea. These passes later became known as the Seven Gates or Seven Entrances of Kamakura, but that name wasn't current in 1333. During the siege of 1333 the Hojo fleet protected the bay, preventing any attempt to attack from the sea.
The city was garrisoned by the remaining Hojo armies in the east. The survivors of the armies defeated at Kotesashi, Kumegawa and Bubaigawara had pulled back to the city. A second Bakufu army had been sent east to raise reinforcements, but that army had also been defeated and forced back to Kamakura.
Although Kamakura was a strong defensive position, its defenders position was hopeless. Their main armies had been sent west. The army of Ashikaga Takauji had changed sides and captured Kyoto, destroying the Shogunate's headquarters at the Rokuhara. The Shogunate army besieging Chihaya had been destroyed while attempting to retreat to safety after learning of the fall of the Rokuhara. News of Nitta Yoshisada's successes encouraged many neutral warriors from the provinces around Kamakura to join his army, although we can probably dismiss the Taiheiki's claim that his army was now 800,000 strong.
Yoshisada split his army into three divisions, taking command of one himself. The first army was to attack the Gokurakuji Passage, to the west of the city. The second attacked the Kobukurozaka Pass in the north. The third, which Yoshisada commanded in person, attacked the Kewaizaka Pass to the north-west of the city. This was perhaps the main approach to the city and led to the road to Musashi Province. The defenders split their army into four, three to face the attacking armies directly and the fourth to act as a reserve.
At dawn on the eighteenth day of the fifth month (30 June 1333) Yoshisada's men lit fires in the villages surrounding the city, causing an alarm in the city. The fighting began during the hour of the snake (the two hour period before noon) and on this first day the defenders generally held their own. The attackers reached Yamanouchi, but this still put them outside the passes.
On the nineteenth day (1 July 1333) Yoshisada's right-hand division came close to the southern edge of the city, but their commander, Odate Muneuji, was killed in a counterattack and his surviving troops pulled back to the west of the city. After this setback there may have been a pause in the fighting, for the next events recording in the Taiheiki take place on the night of the 21st day (3-4 July 133). Nitta Yoshisada led a strong force to the Gokurakuji Passage, where Odate had been killed. The main pass was strongly defended, but in theory it could be outflanked along the coast. The defenders of the city had thought of this. Their fleet was anchored off the shore within arrow-range, while the beach was littered with obstacles.
According to the Taiheiki Nitta Yoshisada cast his gold-mounted sword into the sea and prayed for help from the 'eight dragon-gods of the inner and outer seas'. He was rewarded with an unusually low tide, which allowed his troops to slip past the beach obstacles and also forced the defending ships away from their positions.
The city was now doomed. Yoshisada's men flooded into the city from the south, attacking the defenders of the passes in the rear. Some of the defenders began to surrender or change allegiance, while others committed suicide. Hojo Takatoki set fire to the Bakufu buildings and retreated to the Toshoji Temple.
The fighting finally came to an end on the 22nd day of the 5th month (4 July 1333). The Taiheiki records a series of honourable suicides, although a number of men chose to escape from the city instead. There was also a great deal of hard fighting as outnumbered bands of supporters of the Shogunate attempted to make last stands, but it was now clear that the defenders had failed. Hojo Takatoki killed himself in the Toshoji Temple, and was followed by two hundred and eight three male members of the Hojo clan. The temple was then set on fire, and another six hundred of the temple's last defenders committed suicide.
The fall of Kamakura marked the end of the Kamakura Shogunate, and ensured the victory of the Imperial cause in the Genko War. In the same month Go-Daigo returned to Kyoto, where he began a short period of direct Imperial rule (the Kemmu Restoration). Within a few years he had alienated Ashikaga Takauji, triggering a revolt that would see the Emperor forced to flee from Kyoto for a second time. Once again Nitta Yoshisada would remain loyal, only to be defeated in battle and finally killed during the siege of Kuromaru in August 1338.