Osaka 1615

Tokugawa Ieyasu’s plans
Once he had goaded Hideyori into taking defensive measures in Osaka, Tokugawa Ieyasu moved from a position of exerting political pressure to one of overt military action. His plans for what was to become the Winter campaign were very straightforward. Being in possession of Fushimi and Nijo castles in Kyoto, he needed to move the bulk of his army from Edo under Hidetada, and from Sumpu under his own command, to these two places ready for the final advance against Osaka Castle. Meanwhile, other daimyo would secure positions around Osaka and make themselves ready to join the siege lines when the order came.

The castle’s position, with sea to the west, mountains to the east and rivers to the north, meant that the Tokugawa army could approach Osaka from Kyoto by two routes: along the line of the Yodogawa via Ibaraki Castle, or from the direction of Nara, sheltered by the Ikoma mountain range. If advancing by the latter route, Ieyasu would turn west over the mountains at some point towards Osaka, or make a wider sweep through Nara, Horyoji and Oji, cutting through the mountains at Domyoji, where the Yamatogawa flowed. The open expanse of ground to the south of the castle, where the defences were lightest would provide the best base from which to conduct a siege.


Toyotomi Hideyori’s plans
Nothing shows the lack of unified leadership among the Osaka garrison better than the failure to agree a strategy against the Tokugawa threat. Hideyori essentially had two choices. One was to sit inside Osaka Castle and allow Ieyasu to come to him. The other was to take the fight to the Tokugawa in some way, or at the very least to impede their progress westwards.

Sanada Yukimura and Goto Mototsugu proposed means towards an offensive campaign, and took note of the points discussed above of how the Tokugawa army would approach Osaka. The journey towards Kyoto from the east also allowed certain possibilities for the Tokugawa to be intercepted on the way. The coast road (the Tokaido) and the road through the central mountains (the Nakasendo) joined together shortly before Lake Biwa. From this point all traffic flowed across the Seta bridge, which crossed the Ujigawa as it left the lake. If Kyoto could be secured as well as Seta then the Tokugawa advance would be neutralized. Ishida Mitsunari had attempted a similar strategy in 1600. He had captured the castles of Otsu and Fushimi, and with his rear secure, fought Ieyasu at Sekigahara on the Nakasendo.

With this in mind, Sanada Yukimura and Goto Mototsugu proposed a very bold strategy. While retaining Osaka Castle as a place of safety to which they could retreat if necessary, two armies should advance to secure the approach roads. The first, smaller, force should head east to win control of the Nara passes. The second should secure Ibaraki, and then go on to take Fushimi and then Kyoto itself. There they would secure Nijo Castle and then the imperial palace. With the august emperor in their hands, Tokugawa Ieyasu could be declared a rebel against the throne. This was a strategy that had been adopted on several occasions during the 12th-century wars between the Taira and the Minamoto. Imperial approval would encourage any wavering daimyo to cast their lots with the cause of the dispossessed Toyotomi Hideyori. Taking the bridge at Seta, across which passed the combined roads from the east, would complete the control of the area of the capital. The Tokugawa 'rebels’ would go no further.

This elaborate plan was never put into action. Instead, Hideyori decided to sit tight inside Osaka Castle and allow the Tokugawa a free passage almost to the edge of his defensive line.