The siege of Akasaka (18 February-c.14 March 1333) was one of the few successes won by a massive Bakufu army at the start of the last year of the Genko War (1331-33).
During 1332 the supporters of the Emperor Go-Daigo had inflicted a series of defeats on the Shogunate (or Bakufu). The Shogunate had responded by sending a massive army to Kyoto, pulling their troops out of large parts of Japan in an attempt to crush the revolt before it could spread any further.
On 30 January 1333 the vast Bakufu army was split into three. Aso no Danjo Shohitsu was given command of one of these divisions, and was sent towards Mount Kongo. On its way his army was to attack Akasaka castle, the original home of Kusunoki Masashige, one of Go-Daigo's most able supporters. This castle had already changed hands twice. The Bakufu had captured it in a siege late in 1331 (siege of Akasaka, c.31 October-20 November 1331), and Kusunoki had retaken it in a surprise attack on 28 April 1332 (capture of Akasaka, 1332).
Aso decided to pause for two days at the Tennoji temple (modern Osaka), and launch his attack on the second day of the second month (16 February 1333). As so often was the case two of his men decided to attack before the official time, one to gain more glory and the other because he didn't want to outlive the Shogunate, and believed it to be doomed. Both men were killed in their attack, as was one of their sons who made a solo attack soon afterwards.
The Akasaka castle of 1333 was a very different place to the castle of 1331. That had been a fairly weak fortification, easily reached on three sides. The new castle had been built in a stronger position, and could only be approached from one side. This line of approach was guarded by a wide ditch and a strong wall. This position allowed the defenders to hold off the much larger Bakufu army and inflict heavy casualties on them over a period of thirteen days.
The deadlock was broken when one of the attackers noticed that the defenders seemed to have an ample supply of water, despite there being no obvious source. After digging around the attackers found a tunnel that brought water in from a distance of over a thousand yards. The situation within the castle was soon dire and on the twelfth day after their water supply was cut the defenders decided to make a final sortie from the castle and seek death in battle.
Their commander convinced them not to throw their lives away, arguing that as other castles were still holding out the Bakufu wouldn't want to treat their prisoners too harshly. On the following day the defenders surrendered and 282 warriors went into captivity after a siege of about 26 days. Their hopes of lenient treatment were soon dashed, and they were executed. This example encouraged the resistance of the defenders of Yoshino and Chihaya, and the second of those fortresses would hold out until the end of the war.