Tokugawa had many traits that let him Rise to power, he was careful and bold. He switched alliances during his conquest of Japan. This included Joining the Oda clan,the same group that had kidnapped him as a child. He valued loyalty,often rewarding those who remained loyal. He was often cruel with his conquest of Japan, but had no wish to conquer anything outside of Japan. He eventually united Japan.
Tokugawa Ieyasu was born in Okzaki castle in the modern day province of Aichi, Japan. His father Matsudira Hirotada was part of the Matsudira clan, he was also a powerful Feudal Lord. At age 6, Tokugawa's father was murdered by his own vassals. These Vassals were bribed by the Oda clan.
Although he didn't originally planned to take over Japan, he came to realize that any Feudal lord who was against him, was his enemy. Growing weary of Tokugawa, Ishida Mitsuari plotted to kill Tokugawa. After learning of a plot to kill Tokugawa, most of Japan's Feudal lords turned into two factions. The eastern Group was Tokugawa and his allies, and the western group was Mitsunari and his allies. The led to the battle of Sekihara, where the two sides faced off, eventually Mitsuari was crushed and his allied Feudal lords perused by Tokugawa.
While mostly known for his conquest of Japan, Tokugawa also had many other policies after his son became leader of Japan. Although his son was the leader, Tokugawa still held most of the influence until his death. One of the most notable of these policies was his expulsion and ban of Christianity. He did this for fear of becoming part of the Spanish empire, and a growing Christian population might lean more in favor with them then with Tokugawa. In 1614 he expelled Christianity from Japan.
Tokugawa Ieysau died in 1616 at the age of 73, it is believed he died of cancer or syphilis. After he died he wished to be deified, but his remains were moved. They still do not know where he is buried. After that, his son became emperor and the Tokugawa family ruled Japan until 1870.