The 1571 siege of Fukazawa was one of a number of battles which formed Takeda Shingen's campaigns against the Hōjō clan, during Japan's Sengoku period. Having burned the town of Odawara surrounding the Hōjō home castle two years earlier, he laid siege to a number of other Hōjō holdings in the surrounding provinces, including Fukazawa, in Suruga province. This was the sixth time he had invaded Suruga; Fukazawa was held by Hōjō Tsunanari, who ultimately surrendered just after the lunar New Year, and withdrew to Odawara.