The unification of Japan began with the military conquests of Oda Nobunaga and consolidation efforts of Toyotomi Hideyoshi. After Hideyoshi's death, there was a power struggle between Tokugawa Ieyasu and Ishida Mitsunari. This culminated with <span>Mitsunari's defeat at the Battle of Sekigahara (1600). Tokugawa Ieyasu became the unquestioned ruler of Japan after he defeated the last of the Toyotomi loyalists at the Battle of Osaka (1614 & 1615). </span>