- The rainstorm/thunderstorm
- The intelligence from Yanada Masatsuna
- Nobunaga's small army
- Okehazama itself
Wataru Kajino's Jimoto no Karo ga Kataru Okehazama Kassen Shimatsu ki listed seven key points as well (pp. 45-48).
- Fighting spirit
- Quality of troops
- Others such as charisma
Yanada Masatsuna's intelligence was also a game changer. Once Nobunaga received the information without the bureaucratic chain of command, he went straight for the kill. It was like a shark smelling blood in the water. Both Nobunaga and Masatsuna knew the Okehazama geography very well. After the battle, Nobunaga rewarded Masatsuna with Kustukake Castle and cash.
Nobunaga knew the value of human intelligence and he was successful using the resources he had. Okehazama changed warfare from military exploitation to the age of human intelligence in my opinion.
Nobunaga no tame!