戦国の三人の無名者：信長・秀吉・家康の出自Three Dark Horses Who Dominated the Sengoku Era
Yesterday, we provided an overview of the unique historical period known as the Sengoku era, observing how the actions of Sengoku daimyo (戦国大名, warlords) strangely resemble current trends in AI. Today, without going into too many specifics, we’ll focus on three prominent figures who rapidly gained power during this tumultuous time and ultimately achieved Japan’s first-ever unification.
As briefly outlined yesterday, the Sengoku period began with scattered regional power struggles, eventually shifting towards larger, organized forces as stronger daimyo emerged. This marked the beginning of realistic ambitions for national unification. Interestingly, the key players who rose to prominence were initially overlooked, relatively unknown figures: notably, Nobunaga Oda (織田信長), Hideyoshi Toyotomi (豊臣秀吉), and Ieyasu Tokugawa (徳川家康). The emergence of these three dramatically reshaped Japanese history.
To quickly recap the historical flow: first, Nobunaga Oda initiated the conquest of the Kinai region (Kansai), signaling the beginning of nationwide ambitions. However, Nobunaga was ultimately betrayed by his retainer Mitsuhide Akechi (明智光秀) and committed suicide during the Honnoji Incident (本能寺の変). Following Nobunaga’s death, Hideyoshi Toyotomi swiftly defeated the traitorous Akechi and achieved national unification. Thus, Nobunaga’s life effectively ended just shy of full unification. After Hideyoshi’s death, a decisive conflict over succession—the Battle of Sekigahara—occurred in 1600. Ieyasu Tokugawa emerged victorious, establishing the shogunate in Edo (modern Tokyo), thereby completing the process of national unification. However, even after Ieyasu formally established the Edo Shogunate in 1603, the Toyotomi clan, linked to Hideyoshi, remained formidable, maintaining significant power from their stronghold at Osaka Castle, dominating western Japan. To secure his authority, Ieyasu inevitably needed to eliminate this formidable obstacle. Therefore, Ieyasu initiated two separate wars between 1614 and 1615, ultimately leading to the destruction of the Toyotomi clan.
Broadly speaking, from the onset of the Onin War (応仁の乱, 1467-1477), the number of daimyo rapidly increased, reaching a peak in the mid-16th century. Thereafter, power gradually consolidated, eventually falling entirely under Tokugawa control. This outline broadly captures the essence of the Sengoku period. The remnants of this power balance persisted into the Edo period, reflected through the domain (藩, han) system, wherein the shogunate and domains carefully balanced power. Here, the Tokugawa family strategically enhanced their governance capabilities by skillfully dividing power into three distinct categories.
These previously explained categories are known as shinpan (親藩), fudai daimyo (譜代大名), and tozama daimyo (外様大名). Briefly put, shinpan daimyo were blood relatives of the Tokugawa family, exemplified by the Owari (尾張), Kii (紀伊), and Mito (水戸) domains, collectively known throughout the Edo period as the Gosanke (御三家, “Three Houses”). Being directly related to the Tokugawa, these daimyo frequently served as candidates for the next shogun. Next, fudai daimyo were hereditary retainers who served the Tokugawa before the Edo shogunate’s establishment. Clearly, they were strongly pro-Tokugawa, with notable examples including the Ii (井伊家), Sakai (酒井家), and Sakakibara (榊原家) clans. Fudai daimyo typically occupied critical government positions such as roju (老中, senior councilors) and tairo (大老, chief ministers). However, as the Edo political structure gradually weakened, the increased authority of these fudai daimyo became a direct cause of the turbulent end-of-Edo period. Generally, they held strategically significant territories close to Edo in eastern Japan, bolstering their power through crucial roles in defense and administration.
Lastly, the tozama daimyo were those who had not served the Tokugawa prior to the decisive Battle of Sekigahara and had only submitted afterward. Prominent examples include the Maeda family of Kaga (加賀藩), the Shimazu family of Satsuma (薩摩藩), and the Mori family of Choshu (長州藩). Notably, the Satsuma and Choshu domains, central to the Meiji Restoration, originated from tozama daimyo lineages, shedding light on their motivations for opposing the Tokugawa shogunate in the late Edo period. This situation arose because tozama daimyo controlled extensive territories, effectively autonomous regional powers, yet were systematically excluded from participating in shogunate politics or holding high offices like roju throughout the Edo period.
For these influential local lords and their retainers, exclusion from central power naturally fostered dissatisfaction, inevitably motivating them to seize political control for themselves. These historical grievances were a critical driver behind later anti-shogunate movements. Understanding this dynamic, the Tokugawa carefully managed these powerful factions, enacting various measures to pacify potential rebellions. Consequently, tozama daimyo were generally placed far from Edo, primarily in western Japan, as the shogunate monitored them as potential threats. Conversely, this geographic distancing meant that these domains inherently possessed the latent potential for rapid autonomous growth whenever shogunate authority weakened. This scenario closely mirrors how the Muromachi shogunate, under the Ashikaga family (足利将軍家), swiftly collapsed following internal strife during the Onin War, plunging Japan into the Sengoku period. Ultimately, similar dynamics precipitated the Meiji Restoration, marking the end of the Edo period.
The Sengoku period is a fascinating subject due to the variety of topics it encompasses. From here, we will explore the backgrounds of three entirely unknown individuals who rose to prominence, crucial to understanding Japan’s path to national unification, by focusing specifically on their origins.
Nobunaga Oda (織田信長, 1534-1582), the most prominent of these figures, was born the legitimate heir of Nobuhide Oda (織田信秀, 1508-1551), a Sengoku daimyo of Owari Province (尾張国, modern-day western Aichi Prefecture). While this might suggest Nobunaga had an illustrious pedigree, he actually belonged to a collateral branch of the Oda family, lacking significant status, and thus was nationally unknown. Despite being the heir to a daimyo, Nobunaga’s origins were far from prestigious in the eyes of contemporary warrior society, forcing him to build his own power base within the turbulent Sengoku era. His initial obscurity became a driving force behind his subsequent success, primarily because no one anticipated his meteoric rise. The more powerful daimyo became complacent, creating vulnerabilities that Nobunaga exploited masterfully, rapidly ascending toward the pinnacle of power.
Hideyoshi Toyotomi’s (豊臣秀吉, 1537-1598) background was even more humble. While there are multiple theories about his exact origin, Hideyoshi is commonly believed to have been born into a peasant or ashigaru (足軽) family in Owari. Ashigaru were low-ranking foot soldiers who made up the bulk of a daimyo’s military forces. Hideyoshi initially went by the name Tokichiro Kinoshita (木下藤吉郎). His dynamic rise began as a mere servant soldier performing menial tasks under Nobunaga, his early master. In short, Hideyoshi’s background wasn’t even fully warrior-class, meaning he had to rely purely on his ingenuity and exceptional talent to rise through society. Compared to Nobunaga, who at least had lineage linked to daimyo status, Hideyoshi had to leverage completely different abilities to climb the ranks. Hideyoshi’s unique talents caught Nobunaga’s attention, ultimately propelling him to the apex of power, symbolizing the distinct characteristics of the Sengoku period in Japanese historical consciousness.
Incidentally, the name Hideyoshi Toyotomi was adopted much later. After securing dominance, in 1585 Hideyoshi assumed the prestigious court office of Kanpaku (関白, Imperial Regent) by becoming an adopted member of the aristocratic Fujiwara (藤原) family, receiving the surname “Toyotomi” directly from the Imperial Court, thus formally entering the aristocracy (公卿). Here, once again, the Fujiwara name emerges. Previously, we discussed the rise and fall of the Fujiwara clan, who had served historically as advisors and administrators to the emperor, occupying the highest court positions in Kyoto, and still maintaining substantial prestige within the imperial court. Traditionally, the role of Kanpaku had been hereditary within the Fujiwara clan’s Sekkan-ke lineage (摂関家), but after completing national unification, Hideyoshi leveraged his political influence to pressure the imperial court into granting him the title. By formally receiving the surname Toyotomi from the court, he effectively shed his low-born origins, constructing political legitimacy through traditional authority. This intriguing maneuver shows how Hideyoshi, rising from humble beginnings, relied on established aristocratic tradition to bolster his newly acquired status.
However, Hideyoshi was overly optimistic about the future security of his lineage. After his death, the highly charismatic Hideyoshi’s family swiftly collapsed, primarily due to the actions of Ieyasu Tokugawa (徳川家康, 1543-1616). Originally named Motoyasu Matsudaira (松平元康), Ieyasu was born the son of Hirotada Matsudaira (松平広忠, 1526-1549), lord of Okazaki Castle in Mikawa Province (三河国), adjacent to Owari Province. The Matsudaira clan were minor warlords of Mikawa but were under the control of the powerful Imagawa clan (今川家), who held dominion over the Tokai region and were descendants of the Ashikaga lineage. As a result, Ieyasu’s early life was marked by hardship as a hostage. At six years old, in 1547, he was sent as a hostage to Yoshimoto Imagawa (今川義元) in Suruga Province, and subsequently, at age eight in 1549, he became a hostage of the Oda family in Owari. In the same year, his father Hirotada was murdered by a retainer, effectively subjugating the Matsudaira to Imagawa control. Thus, despite noble birth, Ieyasu faced adversity from an early age, cultivating a determination to free himself from his subjugation under the Imagawa clan and to rise to power independently. His hostage experience, especially in early life, taught him patience and resilience—qualities that would become his greatest strategic assets as he rose to dominate the chaotic Sengoku era.
Similarly to Toyotomi, the Tokugawa (徳川) name was also a later creation resulting from a surname change. However, unlike Hideyoshi who was granted the Toyotomi surname by the imperial court in 1585, Ieyasu Tokugawa changed his surname from Matsudaira (松平) to Tokugawa earlier, in 1566, via the imperial court. Interestingly, at this time, Ieyasu falsely claimed descent from the prestigious Minamoto clan (源氏, Genji lineage). Naturally, due to the chaotic conditions of the Sengoku period, such false lineage claims were not uncommon, as actual genealogies were often obscured. Specifically, Ieyasu declared himself a legitimate descendant of the “Nitta Genji - Serada clan” (新田源氏ー世良田氏), tracing his supposed ancestry back to the renowned warrior Minamoto no Yoshiie (源義家, 1039-1106), through his descendant Minamoto no Yoshishige (源義重, 1128-late 12th century), establishing his lineage within an esteemed samurai family.
But why exactly did Ieyasu choose the Minamoto lineage? I believe the primary reason lies in Ieyasu’s profound understanding of history—arguably his greatest asset in successfully unifying Japan.
The political intention behind Ieyasu’s falsified lineage carried a concealed message: a declaration of opposition against the Muromachi shogunate (室町幕府), specifically targeting the ruling Ashikaga shogun family (足利将軍家). Although significantly weakened, the Ashikaga family and Muromachi shogunate still nominally persisted in 1566. Positioning this old regime as a declining structure, Ieyasu aimed to secure legitimacy for his ambition by aligning himself genealogically with figures predating the Muromachi period—the Minamoto clan associated with the earlier Kamakura shogunate (鎌倉幕府). Through this maneuver, Ieyasu framed his quest for supremacy not as rebellion against the existing order but as a “restoration of Genji authority,” thereby gaining historical legitimacy. From this strategic act alone, it is evident how politically astute and intelligent Ieyasu truly was. Indeed, the ideological foundation underpinning his establishment of the Edo shogunate (江戸幕府) was precisely this: the revival of Minamoto lineage and Kamakura-era governance, directly symbolizing the demise of the Ashikaga-led Muromachi regime.
But what exactly was the “Nitta Genji - Serada clan” lineage that Ieyasu claimed as his own? By exploring this point, we begin to see clearly that the Sengoku period was not merely a chaotic era of warlords competing blindly for dominance. Most significantly, it was Ieyasu Tokugawa—who thoroughly understood history—who ultimately secured lasting hegemony, while all others, no matter how powerful, eventually perished. So, what was Ieyasu’s true strength? And why has understanding history always been vital, both past and present?
In Japan, flamboyant warlords like Nobunaga Oda and Hideyoshi Toyotomi remain popular because they align with the popular, albeit fabricated, image of “heroic samurai,” while Ieyasu Tokugawa is often dismissed as plain and unexciting. Nevertheless, it was Ieyasu who ultimately conquered and shaped his era. What exactly constituted the core of his thinking? Understanding this is essential for grasping not only the complexity of the period before the Edo era but also the entirety of Edo-period history itself.