Sakuma Morimasa

Who They Were

Sakuma Morimasa (佐久間盛政, さくま もりまさ) was a samurai commander of the late Muromachi period and one of the top generals serving Shibata Katsuie, the senior Oda retainer who became one of the most powerful warlords in central Japan after Oda Nobunaga's death in 1582. Morimasa was born in 1554, the son of Sakuma Moritsugu, and belonged to the Sakuma family, a warrior house long tied to the Oda. His mother was a sister of Shibata Katsuie, which made Morimasa Katsuie's nephew and bound the two men by blood as well as by military service.

He is remembered above all for his ferocity in battle. His fighting earned him the nickname oni-genba (鬼玄蕃), "Demon Genba" — Genba being a name he used alongside Morimasa. The nickname stuck because it described how he fought: aggressively, without hesitation, and with a reputation for pressing an advantage hard.

Life and Career

Morimasa was born in 1554, in the 23rd year of the Tenbun era (天文), in Shōwa-ku. His father, Sakuma Moritsugu, was a samurai, and the family was already established in the service of the Oda house. Morimasa's relative Sakuma Nobumori was a prominent Oda retainer who had served both Oda Nobuhide and his son Oda Nobunaga, so Morimasa grew up inside the military network that was consolidating Oda power in central Japan.

He fought in several campaigns, and it was through these that he built his reputation as a fighting commander. His career is inseparable from that of his uncle Shibata Katsuie. After Nobunaga was killed at Honnō-ji in 1582, Katsuie emerged as one of the leading contenders to inherit Oda authority, and Morimasa served as one of his principal generals in the struggle that followed.

That struggle came to a head in 1583 against Toyotomi Hideyoshi, another Oda general who moved faster than his rivals to seize control. Katsuie and Hideyoshi met in the campaign around Shizugatake, where Morimasa commanded a portion of Katsuie's army. Morimasa's death came on July 1, 1583, in the aftermath of that defeat. With Katsuie's cause broken, Morimasa was killed, and the Sakuma general who had been called a demon was gone at twenty-nine.

Why They Matter

Morimasa matters because he stood at the hinge between two ages of Japanese warfare. He was a product of the Oda military machine — a retainer of a retainer, trained in the campaigns that unified central Japan under Nobunaga — and then a commander in the brief, violent scramble that decided who would inherit that unification. The Shizugatake campaign of 1583 was one of the decisive moments of that scramble, and Morimasa was one of its central field commanders on the losing side.

His defeat and death helped clear the way for Toyotomi Hideyoshi. When Katsuie's coalition collapsed, Hideyoshi faced fewer serious rivals on the road to national dominance. Morimasa's career therefore illustrates how quickly fortunes turned in the years around 1582–1583: a general celebrated as a demon in one campaign could be dead within months of his greatest notoriety.

His story also shows how tightly the great warrior houses were woven together by marriage. Morimasa was a Sakuma by birth and a Shibata by blood through his mother, and he fought for his uncle's faction. In this period, family alliance and military allegiance were often the same thing.

The Name in Japanese

The name is written 佐久間盛政. It is read さくま もりまさ in kana, and rendered in romaji as Sakuma Morimasa. The family name comes first, as is standard in Japanese.

Breaking it down character by character:

• 佐 (read sa here) — "assist" or "help." It is a common element in surnames and carries a sense of aiding or supporting.
• 久 (read ku here) — "long time" or "long-lasting." It appears in many names with a wish for endurance or permanence.
• 間 (read ma here) — "interval," "space," or "between." In surnames it often functions as a suffix, and it is the character that ends the family name Sakuma.
• 盛 (read mori here) — "prosperous," "flourishing," or "abundant." It is a frequent element in given names, and it is the first character of his personal name.
• 政 (read masa here) — "government," "rule," or "administration." It is a very common closing element in samurai given names of this era.

So the family name 佐久間 (Sakuma) is built from "assist," "long-lasting," and "interval," while the given name 盛政 (Morimasa) combines "prosperous" with "rule" — a name that reads almost like a wish for successful governance. The nickname oni-genba (鬼玄蕃) uses 鬼, "demon" or "ogre," attached to Genba, the alternate name by which he was also known.

Legacy

Morimasa's legacy rests on two things: his reputation as a fighter and his role in a losing cause. The nickname oni-genba outlived him and became the label by which later accounts identified him — a shorthand for the kind of commander who led from the front and was feared for it. In the memory of the Sengoku conflicts, he belongs to the group of able generals who backed the wrong claimant after Nobunaga's death and were erased by the outcome.

Because he died on July 1, 1583, at the age of twenty-nine, his career was short. He left no long administrative or political record of the kind that sustained the reputations of the victors. What remained was the image of the Demon Genba: a Sakuma commander, nephew of Shibata Katsuie, who fought for his uncle's faction to the end and fell with it.