for Hideyori were Maeda Toshiie, Mōri Terumoto, Ukita Hideie, Uesugi Kagekatsu, and Ieyasu himself, who was the most powerful of the five. This change in the pre-Sekigahara power structure became pivotal as Ieyasu turned his attention towards Kansai; and at the same time, other ambitious (albeit ultimately unrealized) plans, such as the Tokugawa initiative establishing official relations with New Spain (modern-day Mexico), continued to unfold and advance. Death of Hideyoshi and Toshiie Toyotomi Hideyoshi, after three more months of increasing sickness, died on September 18, 1598. He was nominally succeeded by his young son Hideyori but as he was just five years old, real power was in the hands of the regents. Over the next two years Ieyasu made alliances with various daimyo, especially those who had no love for Hideyoshi. Happily for Ieyasu, the oldest and most respected of the regents, Maeda Toshiie, died after just one year in 1599. Unification of Japan (1599–1603) Conflict with Mitsunari With the death of Toyotomi Hideyoshi in 1598 and Maeda Toshiie in 1599, Ieyasu led an army to Fushimi and took over Osaka Castle, the residence of Hideyori. This angered the three remaining regents and plans were made on all sides for war. Opposition to Ieyasu centered around Ishida Mitsunari, one of Hideyoshi's Go-Bugyō, or top administrators of Hideyoshi's government and a powerful daimyo who was not one of the regents. Mitsunari plotted Ieyasu's death and news of this plot reached some of Ieyasu's generals. They attempted to kill Mitsunari but he fled and gained protection from none other than Ieyasu himself. It is not clear why Ieyasu protected a powerful enemy from his own men but Ieyasu was a master strategist and he may have concluded that he would be better off with Mitsunari leading the enemy army rather than one of the regents, who would have more legitimacy. Nearly all of Japan's daimyo and samurai now split into two factions—the Western Army (Mitsunari's group) and the Eastern Army (Ieyasu's group). Ieyasu supported the anti-Mitsunari group, and formed them as his potential allies. Ieyasu's allies were Katō Kiyomasa, Fukushima Masanori, Mogami Yoshiaki, Hachisuka Iemasa, the Kuroda clan, the Hosokawa clan and many daimyo from eastern Japan. Mitsunari allied himself with the three other regents: Ukita Hideie, Mōri Terumoto, and Uesugi Kagekatsu, as well as with Ōtani Yoshitsugu, Chosokabe clan, Shimazu clan and many daimyo from the western end of Honshū. War