Sakakibara Yasumasa

Who They Were

Sakakibara Yasumasa (榊原康政, さかきばら やすまさ) was a samurai and daimyō — a landed military lord — who served the Tokugawa clan across the violent transition from the Sengoku period of civil war into the settled Tokugawa shogunate. Born in 1548 in Mikawa Province, the Tokugawa heartland in what is now eastern Aichi Prefecture, he died in Edo on 19 June 1606. His life thus spans almost exactly the decades in which Japan was unified under first Oda Nobunaga, then Toyotomi Hideyoshi, and finally Tokugawa Ieyasu.

He was counted among the Tokugawa family's "Four Guardian Kings" (四天王, shitennō), the four commanders most trusted by Ieyasu. The other three were Sakai Tadatsugu, Honda Tadakatsu and Ii Naomasa. That grouping placed Yasumasa at the centre of nearly every major Tokugawa campaign of the late sixteenth century.

Life and Career

Yasumasa was born in 1548, in the seventeenth year of the Tenbun era (天文), to Sakakibara Nagamasa. His mother was of the Dōke family. He grew up in Mikawa Province among the same generation of Tokugawa retainers who would later command armies, and he entered Tokugawa service young.

His reputation rested on battlefield command. At the Battle of Anegawa, fought between the allied forces of Oda Nobunaga and Tokugawa Ieyasu against the Azai and Asakura clans, Yasumasa executed a flanking manoeuvre that turned the course of the fighting. It became the action for which he was best known as a tactician.

Between 1574 and 1579 he campaigned in Tōtōmi Province, where he captured a string of castles held by the Takeda clan. Reducing those strongholds one by one stripped the Takeda of their western defences and formed part of the wider Tokugawa pressure on Takeda territory in that decade.

Under Toyotomi Hideyoshi's national government he held the court title Shikibu-Shō (式部大輔), an office associated with the Ministry of Ceremonial. When Ieyasu established the Tokugawa shogunate after his victory at Sekigahara in 1600, Yasumasa was appointed a Rōjū (老中) — a senior elder councillor, one of the small group of daimyō who advised the shogun directly on governance. He held that position until his death in Edo in 1606.

He married a daughter of Ōsuga Yasutaka. Among his children were Sakakibara Yasukatsu, Sakakibara Tadanaga, Ōsuga Tadamasa, and two daughters, one of whom became the wife of Sakai Tadayo.

Why They Matter

Yasumasa belongs to the generation that converted a regional warlord house into a national government. The Tokugawa victory was not the work of Ieyasu alone; it depended on a cadre of commanders who could win battles, hold newly taken territory, and then administer it. Yasumasa did all three.

His career also marks the moment when military service turned into civil office. The same man who flanked an enemy line at Anegawa and took Takeda castles in Tōtōmi sat on the Rōjū under the shogunate. That shift — from battlefield retainer to elder councillor — is the shape of early Edo politics, and Yasumasa's biography is a clean example of it.

His inclusion among the Four Guardian Kings gave later Japanese culture a fixed set of names. The phrase shitennō itself borrows from Buddhist vocabulary, where it denotes the four guardian kings of the cardinal directions; applying it to Ieyasu's commanders cast them as the protectors of a new order.

The Name in Japanese

The full name is written 榊原康政. It is read さかきばら やすまさ in kana, and romanised as Sakakibara Yasumasa. The family name comes first, as is standard in Japanese.

榊 — read saka here. This kanji is a Japanese-made character (kokuji), assembled from the tree radical 木 and the deity character 神. It names the sakaki tree, an evergreen sacred in Shintō and used to decorate altars. It is a rare character in ordinary text, and it appears in very few surnames.

原 — read bara here, though the character's usual readings are hara or gen. It means "plain", "field" or "meadow". The shift from hara to bara is a voicing change (rendaku) that happens when characters combine in a compound. So 榊原 as a whole means something like "sakaki field".

康 — read yasu. It means "peace", "health" or "ease". It is a common element in male given names of the period, and it was frequently granted by a lord to a retainer as a mark of favour.

政 — read masa. It means "government", "administration" or "politics". Like 康, it is a standard building block of samurai given names.

The given name 康政 can therefore be read as a pairing of "peace" and "governance" — an auspicious combination rather than a descriptive phrase. Note that the family name 榊原 and the given name 康政 are separate units; Japanese does not space them, but the boundary falls between 原 and 康.

Legacy

Yasumasa died in Edo on 19 June 1606, only a few years into the shogunate he had helped to build. His descendants continued as daimyō, and the Sakakibara name remained in the Tokugawa order he had served.

His standing in Japanese historical memory rests on two things: the flanking attack at Anegawa, and the list of four names. The Four Guardian Kings became a standard way of describing the Tokugawa military elite, and Yasumasa's place in it kept him visible in accounts of the period long after the battles themselves were over.