In 1578 Oda Nobunaga called on his retainers to attack the Mōri clan. Nagaharu almost decided to ally with the Oda clan, but after hearing that the low-born general Hashiba Hideyoshi, whom he did not respect, was leading the troops, he revolted and instead allied himself with Hatano Hideharu of Tanba province.
Nagaharu took a stand at Miki Castle, and was besieged by Hideyoshi's troops on the orders of Nobunaga. The Siege of Miki[1] did not go well for Hideyoshi, and with a revolt by Araki Murashige and the help of the Mōri clan, Nagaharu successfully repelled the Oda force.
In 1579, Hideyoshi returned and instead of launching a direct assault, he launched multiple sieges against smaller castles like Kamiyoshi Castle and Sigata Castle to cut off the support from Mōri. This led to a rapid depletion of food, and in 1580, with no hope of another reinforcement from Mōri clan, Nagaharu committed seppuku in exchange for the lives of the troops in Miki Castle.
