Why did Iemitsu's younger brother, Tokugawa Tadanaga, commit suicide? After being rejected as a candidate for shogun, he repeatedly committed foolish acts.

Looking back at history, the relationship between brothers has often been a fatal problem. The biggest reason is the very practical one: "If we don't decide on a successor quickly, someone will find fault with him and bring him up." Oda Nobunaga is an easy example to understand. The conflict between Nobunaga and his younger brother, Oda Nobukatsu (Nobuyuki), began when some of his retainers thought that "Nobunaga-sama would not be good" and brou…