Oshi Castle

Oshi Castle (忍城) is a part of the Hōjō's territory during Hideyoshi's siege of Odawara Castle. Known as a structure that matched the qualities of its larger cousin, Oshi Castle blocked one of the planned paths for surrounding the Hōjō's main keep.

Historically, Ujinaga Narita led a valiant resistance against the Toyotomi forces, who gravely outnumbered his own defenders. Mitsunari led the siege against the castle for Hideyoshi's troops, marking the campaign as his first strategic blunder and a stain on his name. According to legends, Kaihime's main achievement in history involved fighting alongside her father to drive the opposition back.

Samurai Warriors
In Samurai Warriors 3, this battle acts as the replacement of Odawara Castle in various characters' stories. This is the last battle between the Hōjō and the other clans with Ujiyasu acting as the leader. The main focus of the battle revolves around the Hōjō's water attack, which involve breaking apart the embankments in the middle of the map. Kai is the one who is mainly responsible for destroying the fortification. When this occurs, the map will be changed to isolate the Toyotomi troops.

The Hōjō's scenario can be first played in Kai's story. The water attack is the key to their victory so their first goal is to defend it their position against the advance Toyotomi forces (Kanetsugu, Keiji, Sakon, and company). An engineering unit appears and needs to be guarded and escorted to construction site. Gracia's scenario in the Xtreme Legends expansion has her instead focus on defeating the pursuing Toyotomi generals for the water attack's success. She also has a secondary objective of beating her conflicted husband.

If they should succeed, the Toyotomi numbers will be cut down significantly and the Hōjō's army can charge for a turnaround victory. Failing the water attack signals a diverse plummet of Hōjō morale and the danger of the main camp being overrun by Toyotomi generals.

The Toyotomi side, which is the side seen for the majority of the cast's Story Modes, offers a chance to strike back after the water attack succeeds. The first mission often demands a break through of the Hōjō's defense by defeating Ujikuni Hōjō or Ujinaga Narita. Once the water attack succeeds, a mission to defeat Kai or Kotarō is triggered. They need to be defeated in order to return to the main camp's defense, which may be in danger of being overrun by the entire Hōjō army. When the main camp is saved, the Toyotomi can then lead their troops against Ujiyasu for their victory. Yukimura, Keiji, Kunoichi, Mitsunari, Sakon, and Kanetsugu are the only ones to get the Toyotomi side as part of their story.

A few minor differences can occur based on the character being used. Keiji and Sakon's version of the battle offers a chance to prevent the water attack by rescuing their comrades and quickly defeating Kai. In Keiji's version, Toshie is also present for the Toyotomi side, while in Yukimura's, Ina is present for the Toyotomi.

Nobunaga's Ambition
The newest title, Nobunaga no Yabou Tendou with Power Up Kit, includes a bonus scenario dedicated to the battle. It is a collaborative tie in with the 2012 live action film, Nobou no Shiro. Players can choose to side with the Narita army or the Toyotomi troops for the battle.

Historical Information
In 1590, during Hideyoshi's siege of Odawara Castle, the Toyotomi army surrounded the nearby Oshi Castle with 3,000 men. There were only 300 men fortifying the castle's defenses and Kaihime's seventy-one year old grandmother (and mother in some accounts) was said to have taken charge of the strategic planning of the castle's defense. The defenders successfully remained resilient to the invaders' attacks, mainly due to the marshlands and steep ditches that surrounded the castle.

In June, Ishida Mitsunari marched with 20,000 men in an attempt to take the fortification. He ordered the castle to be burned down but, due to the moist environment and high morale of the defending army, it was nearly impossible to start a blaze. Opting for a frontal assault, Mitsunari marched his men through the banks near Takamatsu Castle. The Narita vassals saw their opening and broke the river's dam, greatly demolishing Mitsunari's numbers. The fleeing soldiers were chased away by Narita vassals.

The castle defenses remained strong until Hōjō Ujimasa's surrender at Odawara. Ujinaga then chose to follow suite.