What was the Second Battle of Ueda?
While the main armies converged on Sekigahara, Tokugawa Ieyasu's son and heir Hidetada took the inland road with 38,000 men — most of the veteran Tokugawa army — and stopped to reduce a small castle at Ueda held by Sanada Masayuki and his younger son Sanada Nobushige.
He never took it, and he arrived at Sekigahara days after the battle was over. It is the most consequential delay in Japanese military history.
Why did it happen?
The Sanada had been ordered to join the Tokugawa march. On the road, word came that the Western Army had risen, and the family split: Masayuki and his younger son turned back to Ueda for the Toyotomi cause, while the elder son Sanada Nobuyuki stayed with the Tokugawa.
Hidetada had orders to move on the capital. Whether he was also authorised to deal with Ueda on the way is one of the things historians argue about; what is certain is that he stopped.
Masayuki had beaten a Tokugawa army at the same castle in 1585, which made Ueda a matter of reputation as well as strategy.
Forces and sides
Hidetada's army is consistently given as around 38,000. The Ueda garrison is usually estimated at 2,000 to 3,000, though the figures vary.
What happened?
The Sanada opened with negotiations that went nowhere, buying days. When the siege began, they used the terrain — the Chikuma river, the ravines, the surrounding paddy fields — and repeated small sorties to draw attackers into ground where numbers could not be used.
The traditional accounts describe deliberate feigned retreats that pulled Tokugawa troops into prepared killing ground, and the flooding of approaches. The details vary between sources, but the pattern of a small mobile garrison refusing to be pinned is consistent.
After several days, Hidetada received his father's order to come south immediately. He left a covering force and marched — and arrived at Sekigahara after the battle had been decided.
Turning point
There was no assault that decided it. The Sanada won by making a quick success impossible, and by being interesting enough that a young commander with everything to prove kept trying.
Outcome
Ieyasu is recorded as being furious, and refused to see his son for some days. Hidetada nevertheless became the second shogun in 1605.
Masayuki and Nobushige were condemned and then, at Nobuyuki's request and with the backing of Honda Tadakatsu, exiled to Kudoyama instead of executed. Fourteen years later Nobushige came out of that exile to fight at the Siege of Osaka.
Why it mattered
Sekigahara was won without the Tokugawa main army, which meant Ieyasu owed the victory to allies rather than to his own household troops — a fact that shaped how generously, and how carefully, he redistributed land afterwards.
For the Sanada, Ueda is the foundation of a reputation that has lasted four centuries: the small house that beat the largest army in Japan twice on the same ground.
