Nobunaga and Ieyasu Defeat the Takeda at Nagashino

In June 1575, Takeda Katsuyori led an army of about 15,000 men into Mikawa Province and besieged Nagashino Castle. Defended by roughly 500 troops under Okudaira Sadamasa, the fortress occupied a vital strategic transport route that Tokugawa Ieyasu had seized from the Takeda clan. Facing an overwhelming adversary, Ieyasu mobilised his own forces and appealed for urgent assistance from his powerful ally, Oda Nobunaga. After pausing hostilities against his own rivals in central Japan, Nobunaga marched from Gifu, and the combined Oda and Tokugawa relief force is usually put at about 38,000 men, joining Ieyasu at Okazaki before establishing defensive positions at Shitaragahara, a few kilometres west of the besieged castle.

Rather than advancing directly to relieve the fortress, the allied commanders chose to wait on defensible ground. Katsuyori left about 3,000 men to maintain the siege and advanced with his remaining 12,000 to confront them across the Rengo River. Meanwhile, allied forces erected palisades and earthworks to halt enemy charges. Nobunaga also dispatched a nocturnal raiding party under Tokugawa vassal Sakai Tadatsugu, several thousand strong, to strike the Takeda garrison at Mount Tobigasu. That surprise attack overran the Takeda positions at Tobigasu and, together with a sortie from the garrison, relieved Nagashino Castle.