quality:corruption
Conflict with Hideyori

The last remaining threat to Ieyasu's rule was Toyotomi Hideyori, the son and rightful heir to Hideyoshi. He was now a young daimyo living in Osaka Castle. Many samurai who opposed Ieyasu rallied around Hideyori, claiming that he was the rightful ruler of Japan. Ieyasu found fault with the opening ceremony of a temple (Great Buddha of Kyoto) built by Hideyori; it was as if he prayed for Ieyasu's death and the ruin of the Tokugawa clan. Ieyasu ordered Hideyori to leave Osaka Castle, but those in the castle refused and summoned samurai to gather within the castle. Then in 1614, Tokugawa besieged the Osaka Castle against Hideyori.

The Tokugawa forces, with a huge army led by Ieyasu and shōgun Tokugawa Hidetada, laid siege to Osaka Castle in what is now known as "the Winter Siege of Osaka". Eventually, the Tokugawa were able to force negotiations and an armistice after directed cannon fire threatened Hideyori's mother, Yodo-dono. However, once the treaty was agreed, the Tokugawa filled the castle's outer moats with sand so his troops could walk across. Through this ploy, the Tokugawa gained a huge tract of land through negotiation and deception that they could not through siege and combat. Ieyasu returned to Sunpu Castle, but after Toyotomi Hideyori refused another order to leave Osaka, Ieyasu and his allied army of 155,000 soldiers attacked Osaka Castle again in "the Summer Siege of Osaka".

Finally, in late 1615, Osaka Castle fell and nearly all the defenders were killed, including Hideyori, his mother (Toyotomi Hideyoshi 's widow, Yodo-dono), and his infant son. His wife, Senhime (a granddaughter of Ieyasu), pleaded to save Hideyori and Yodo-dono's lives. Ieyasu refused and either required them to commit ritual suicide, or killed both of them. Eventually, Senhime was sent back to the Tokugawa alive. With the Toyotomi line finally extinguished, no threats remained to the Tokugawa clan's domination of Japan.