Oshi Castle

The Battle of Oshi Castle (忍城の戦い, romaji: Oshijō no Tatakai) 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.

In Samurai Warriors 4, the Toyotomi side is available for the Legend of the Sanada storyline, while the Hojo side is available in the Legend of Kanto storyline. For the Toyotomi side, Yukimura Sanada, Kanetsugu Naoe, Nobuyuki Sanada, Yoshitsugu Otani, Kagekatsu Uesugi, Kunoichi, Mitsunari Ishida, Sakon Shima, and Ina are the option as playable characters, while for the Hojo side, Lady Hayakawa, Kai, Ujiyasu Hojo, and Kotaro Fuma are the option as playable characters.

For the Toyotomi side, the player will need to start by escorting Tadaoki Hosakawa and Yoshiaki Kato to the Southwestern Garrison in order to flood the area around it. After the area is flooded, Kai will order the Hojo officers to destroy the levee, so the player will need to stop the officers from doing so. After the player stop the officers, another flood attack will happen at the Northeast of Oshi Castle, while Kai will send Yukie Sakamaki to destroy the levee. At the same time, Kotaro Fuma will order his ninjas to go and support Yukie, so defeating them is an option to send Yukie into panic mode. Even after Yukie and the ninjas are defeated, Mitsunari realized that they can't hurt innocent people, so he order the allied officers to withdraw to let the Hojo break the levee. Once the levee is broken, all the water is drained from the battlefield, and the area around the Southwestern Garrison and the Northeast area of Oshi Castle is accessible once again. However, the Southeeastern part of Oshi Castle is now flooded instead, causing Nagashige Niwa and Yasuharu Wakisaka to withdraw. Kai, together with Lady Hayakawa and the enemy officer will then launch a full attack, therefore defeating them is necessary to protect the allied main camp. After all of them are defeated, Ujiyasu Hojo will appear and head to the main keep, where Nagachika Narita is residing, so the player will need to stop him from doing so. At the same time, Hojo reinforcements from Odawara arrives, led by Ujikuni Hojo, while Kotaro Fuma launch an ambush on the allied main camp. Defeating them and Nagachika is neccesary to bring victory to the Toyotomi side.

For the Hojo side, the flood attack has already happened as the player needs to save the peasants in the front lines from enemy officers. After the peasants are rescued, they will need to be escorted to the levee, while at the same time, stop Yoshitsugu Otani from reaching it. After Yoshitsugu's defeat, the peasants will destroy the levee, causing the water to be drained from the battlefield. After that, Mitsunari Ishida, leading the Toyotomi army, will order his army to advance, as the player will need to stop Kanetsugu Naoe and Yoshinobu Satake from reaching the Western Garrison, preventing Yukimura Sanada from reaching the main keep if playing as Kotaro, defeat the enemy reinforcements from Odawara lead by Ina to prevent joining up with Nobuyuki Sanada, and defeat Kunoichi and Kagekatsu Uesugi. Once all of them are defeated, the enemy main camp will open, as Sakon Shima shows up to protect Mitsunari. Defeat Sakon will cause Mitsunari to go into a state of panic, while defeating Mitsunari will bring victory to the Hojo.

In Samurai Warriors 4-ii, the Toyotomi side is available for Yoshitsugu and Kagekatsu's story, while for the Hojo side, it is available for Lady Hayakawa's story. It plays out mostly the same from the original title for the Toyotomi side, except that it has way more focus for each of the following character based on the story. For the Hojo side, Ujiyasu already passed away during Lady Hayakawa's story, so only her, Kai and Kotaro are available in the stage, with Lady Hayakawa getting more focus then usual, but the battle still play out mostly the same from the original title.

The battle appears as the final part of Spirit of Sanada's Odawara chapter, where Yukimura and Chacha are asked by Mitsunari to assist in dealing with the castle's defenders. Mitsunari will first order the troops in the south to lure out the enemy officers to the flood area before attempting to move on to the northeastern area, which is under attack from Lady Hayakawa's forces.

After the second flood is completed, however, Kai breaks the levee of the Toyotomi forces, causing the water to overflow to their side of the field, and Lady Hayakawa reappears to charge the enemy with Kai. With no choice, Mitsunari is forced to order a head-on attack and after fighting bitterly, make it to Oshi castle. Kotarō then appears and ambushes the Toyotomi troops while leaving the rest of the Hōjō army to charge straight for the Toyotomi main camp. Once the Narita forces are subdued, a Hōjō messenger arrives to report the fall of Odawara, causing the defenders to immediately surrender.

If Kai's engineers are found before the completion of both flood attacks, the levee will remain intact and the Hōjō forces will lead a charge instead. It is not possible to stop Kai's plan, however, in the first time playing stage.

For the battle's strategies:


 * Sasuke will taunt the officers stationed at the south
 * Additional boats will be provided for Hideie Ukita's unit for the flood attack
 * Rallying of the soldiers in the allied main camp
 * If Kai's plan is successfully stopped, Chacha will break the levee herself to stop the Hōjō's assault and surprise them.

Warriors Orochi
In Warriors Orochi 4, it is fused as the northern port with Baidi Castle.

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.