1562: The Formation of the Kiyosu Alliance
Having slain Imagawa Yoshimoto at Okehazama, Oda Nobunaga met with Matsudaira Motoyasu (the future Tokugawa Ieyasu), who was breaking away from Imagawa control, at Kiyosu Castle, and the two concluded a mutual defense pact. The Kiyosu Alliance would hold firm for roughly twenty years until Nobunaga's death at Honnō-ji, a remarkably stable partnership by the standards of the Sengoku period.
Events this year
Month 1
Hōjō forces under Ōta Yasusuke surrounded Kasai Castle. After holding out for roughly two months, it fell in late April. A senior officer of the Awa-Satomi fell during this siege.
Sources さいたま市「岩槻城跡を探る（中編・下）」
Month 3
In the battle against the Hatakeyama, Miyoshi Jikkyū was killed near Kumeda-ji. Many explanations cite the date as the 5th day of the third month, but official materials from Kishiwada City record only the month.
Sources 岸和田市「三好実休の碑」
Month 11
Hōjō Ujiyasu, with Takeda Shingen's support, besieged Matsuyama Castle. After roughly three months of siege, it fell in February 1563.
Sources さいたま市「岩槻城跡を探る（中編・下）」
Matsudaira Motoyasu and Oda Nobunaga met at Kiyosu Castle and formed an alliance, allowing Motoyasu to focus on Mikawa and Nobunaga on Mino.
The Later Hōjō issued regulations for the market before Iizumi Kannon, prohibiting levies, forced purchases, violence, and quarrels in order to regulate trade and public order.
Sources おだわらデジタルミュージアム「郷土読本 小田原」