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. Siege of Osaka The Tokugawa forces, with a huge army led by Ieyasu and shōgun 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 Tokugawa alive. With the Toyotomi line finally extinguished, no threats remained to the Tokugawa clan's domination of Japan. Death In 1616, Tokugawa Ieyasu died at age 73. The cause of death is thought to have been cancer or syphilis. The first Tokugawa shōgun was posthumously deified with the name Tōshō Daigongen (), the "Great Gongen, Light of the East". (A Gongen is believed to be a buddha who has appeared on Earth in the shape of a kami to save sentient beings). In life, Ieyasu had expressed the wish to be deified after his death to protect his descendants from evil. His remains were buried at the Gongens' mausoleum at Kunōzan, Kunōzan Tōshō-gū (). As a common view, many people believe that after the first anniversary of his death, his remains were reburied at Nikkō Shrine, Nikkō Tōshō-gū (), and his remains are still there. Neither shrine has offered to open the graves, so the location of Ieyasu's physical remains is still a mystery. The mausoleum's architectural style became known as gongen-zukuri, that is gongen-style. He