Oda Nobunaga was first recognised as a major daimyo (lord or king) after the
Battle of Okehazama
, in which Nobunaga and hisforce of about 3,000 obliterated and enemy army of about 25,000 troops.
After that, Oda Nobunaga was well on his way to conquering all of Japan (about one third of the land was under his control) when he was assasinated on June 21, 1582 by one of his own generals. Only a little while later was the assasin and his army hunted down and slain by a different general who was loyal to Nobunaga, and so, that general, Toyotomi Hideyoshi, siezed most of the land that Nobunaga preveously owned (which enraged Nobunaga's son, who was suppost to inheret his father's land).