What was the Battle of Yamazaki?
Yamazaki is the battle in which Toyotomi Hideyoshi destroyed Akechi Mitsuhide eleven days after Mitsuhide had killed Oda Nobunaga. It made Hideyoshi the avenger of his lord and, more importantly, the man in possession of the capital.
The battle itself was short. What made it possible was the march that preceded it — the Chugoku Ogaeshi, the "great return from the Chugoku region" — in which Hideyoshi brought an army roughly 200 kilometres east in a handful of days.
Why did it happen?
Hideyoshi was besieging Takamatsu Castle in Bitchu, deep in Mori territory, when word of Nobunaga's death reached him. He concealed the news, concluded an immediate peace with the Mori on terms that looked generous, and turned east.
Mitsuhide, meanwhile, had failed to secure the alliances he needed. He was still consolidating the capital region when he learned that an army he thought was a week's travel away was already close.
Forces and sides
Hideyoshi's force is usually given as 20,000 to 40,000, swollen by Oda contingents that joined him on the march, against roughly 10,000 to 16,000 for Mitsuhide. The imbalance was as much political as numerical: men who might have joined Mitsuhide joined Hideyoshi instead.
What happened?
The ground at Yamazaki is a narrow corridor between the Yodo river and Mount Tennozan, with the road to Kyoto running through it. Both sides understood that whoever held the high ground on Tennozan controlled the passage.
Hideyoshi's troops took the mountain first. The Akechi position along the Enmyoji river was then attacked frontally and from the flank, and after a few hours of fighting it broke.
Mitsuhide fled towards his castle at Sakamoto. The standard account has him killed on the way at Ogurusu, near Kyoto, by armed villagers hunting stragglers.
Turning point
Taking Tennozan. The phrase "the Tennozan of..." is still used in Japanese to mean the decisive contest in a series — a sports championship, an election — and it comes from this battle.
Outcome
The Akechi cause ended within days. Mitsuhide's ally and relative Akechi Hidemitsu was killed at Sakamoto; the family was destroyed.
Hideyoshi entered Kyoto as the man who had avenged Nobunaga, which gave him standing at the Kiyosu conference later that month where the Oda succession was decided — and where he got his way.
Why it mattered
Yamazaki, more than any battle Hideyoshi fought later, is why he became the successor rather than one of several claimants. Speed converted a subordinate general into the arbiter of the Oda house.
The next stage of the same contest was fought against Shibata Katsuie at the Battle of Shizugatake the following year.
