Historical analysis of the rivalry between Hideyoshi and Katsuie

Historical research and analysis suggest that the marriage between Shibata Katsuie and Oichi, the sister of Oda Nobunaga, was not a romantic or defensive union against Toyotomi Hideyoshi, as often depicted in popular dramas. Instead, historical documents like the "Nanko Zatsuroku" suggest the marriage was a political arrangement agreed upon by Hideyoshi and Katsuie during the Kiyosu Conference.

Following the death of Oda Nobunaga at Honno-ji, Hideyoshi demonstrated significant political maneuvering to outpace senior vassals like Katsuie. While Katsuie supported Nobunaga's grandson Nobutaka, Hideyoshi successfully positioned himself by championing Nobutada's son, Sanpōshi.

Evidence indicates that Hideyoshi may have facilitated the marriage as part of a broader territorial reallocation, possibly exchanging Nagahama Castle for the union. Despite these initial agreements, Hideyoshi later took unilateral actions, such as forcing through Nobunaga's funeral arrangements, which ultimately contributed to the conflict that led to Katsuie's downfall.