Tokugawa Ieyasu was very critical of Toyotomi Hideyoshi's expansionism and invasion of Korea. He wisely avoided getting involved in Hideyoshi’s war in Korea by saying that he needed to stay and maintain his position in Japan. His strategy was to strengthen and maintain his rulership, rather than try to expand.
Ieyasu’s outstanding characteristic was his patience. Oda Nobunaga, Hideyoshi and Ieyasu are often compared by historians. If a song bird would not sing, Oda Nobunaga would cut off its head. Hideyoshi would say, “I’ll force the bird to sing,” but Ieyasu would say, "I will wait until this bird sings.”
Hideyoshi and Ieyasu’s great accomplishment was to unify Japan, and Ieyasu then established a strong central government which kept Japan unified for the next 250 years, until the Meiji Restoration
restored the emperor to the central position. This unity of Japan was one of major factors that protected Japan from being colonized by Western powers. The Tokugawa government's policy of banning Christianity was unfortunate from a religious perspective, but it kept Japan out of the political agenda of Western colonialism