At some point during the late 1560s, Ieyasu expanded his domain eastward as a result of the Imagawa family's territory diminishing. Due to the expansion, Ieyasu moved his headquarters to Hamamatsu, a coastal town he turned into a thriving commercial and strategic territory. By the early 1580s, Ieyasu became a major daimyo with vast, fertile territories after surviving an endemic war thanks to his alliance with Oda Nobunaga. After the suicide of Oda Nobunaga, his general Toyomoto Hideyoshi assumed his position and Tokugawa became his rival. After a few battles, Ieyasu offered his fealty to Toyomoto which was accepted, leaving Tokugawa's domain whole. Ieyasu spent time strengthening his vassal forces, increasing the reliability of his administration, and his territories' productivity while Hideyoshi extended his reach to the daimyo of southwest