Nobunaga. Hideyoshi later moved to the port at Imahama on Lake Biwa, where he began work on Imahama Castle and took control of the nearby Kunitomo firearms factory that had been established some years previously by the Azai and Asakura. Under Hideyoshi's administration, the factory's output of firearms increased dramatically. Later, Hideyoshi participated in the 1573 siege of Nagashima. In 1574, Hideyoshi along with Araki Murashige, captured Itami Castle and later in 1575, fought in the Battle of Nagashino against the Takeda clan. In 1576, he took part at the Siege of Mitsuji part of the eleven-year Ishiyama Hongan-ji War. Later, Nobunaga sent Hideyoshi to Himeji Castle to conquer the Chūgoku region from the Mori clan. Hideyoshi then fought in the Battle of Tedorigawa (1577), the siege of Miki (1578), the siege of Tottori (1581) and also Siege of Takamatsu (1582). Death of Nobunaga During the Siege of Takamatsu, on June 21, 1582, Oda Nobunaga and his eldest son and heir, Nobutada, were killed in the Honnō-ji incident by the forces of the traitorous Akechi Mitsuhide. Their assassination in Honnō-ji temple in Kyoto ended Nobunaga's quest to consolidate centralised power in Japan under his authority. Hideyoshi, seeking vengeance for the death of his lord, made peace with the Mōri clan and thirteen days later met Mitsuhide and defeated him at the Battle of Yamazaki, avenging his lord (Nobunaga) and taking Nobunaga's authority and power for himself. Rise to power (1582–1585) Construction of Osaka Castle In 1582, Hideyoshi began construction of Osaka Castle. Built on the site of the temple Ishiyama Hongan-ji, which was destroyed by Nobunaga, in 1597, construction was completed and the castle would become the last stronghold of the Toyotomi clan after Hideyoshi's death. Conflict with Katsuie In 1583 Hideyoshi was in a very strong position. He summoned the powerful daimyō to Kiyosu Castle so that they could determine Nobunaga's heir. Oda Nobukatsu and Oda Nobutaka quarreled, causing Hideyoshi to instead choose Nobunaga's grandson Samboshi, whose other name was Hidenobu. Having won the support of the other two Oda clan elders, Niwa Nagahide and Ikeda Tsuneoki, Hideyoshi established Hidenobu's position, as well as his own influence in the Oda clan. He distributed Nobunaga's provinces among the generals and formed a council of four generals to help him govern. Tension quickly escalated between Toyotomi Hideyoshi and Shibata Katsuie, and at the Battle of Shizugatake in the following year, Hideyoshi