Tokugawa Ieyasu was born in Okazaki Castle in Mikawa on the 26th day of the twelfth month of the eleventh year of Tenbun, according to the Japanese calendar. Originally named Matsudaira Takechiyo (松平 竹千代), he was the son of Matsudaira Hirotada (松平 広忠), the daimyo of Mikawa of the Matsudaira clan, and Odainokata (於大の方), the daughter of a neighboring samurai lord Mizuno Tadamasa (水 野 忠政). His mother and father were step-siblings. They were just 17 and 15 years old, respectively, when Ieyasu was born. Two years later, Odainokata was sent back to her family and the couple never lived together again. As both husband and wife remarried and both went on to have further children, Ieyasu in the end had 11 half-brothers and sisters.

The Matsudaira family was split in 1550: one side wanted to be vassals of the Imagawa clan, while the other side preferred the Oda. As a result, much of Ieyasu's early years were spent in danger as wars with the Oda and Imagawa clans were fought. This family feud was the reason behind the murder of Hirotada's father (Takechiyo's grandfather), Matsudaira Kiyoyasu (松平 清康). Unlike his father and the majority of his branch of the family, Ieyasu's father, Hirotada, favored the Imagawa clan.

In 1548, when the Oda clan invaded Mikawa, Hirotada turned to Imagawa Yoshimoto, the head of the Imagawa clan, for help to repel the invaders. Yoshimoto agreed to help under the condition that Hirotada send his son Ieyasu (Takechiyo) to Sumpu as a hostage. Hirotada agreed. Oda Nobuhide, the leader of the Oda clan, learned of this arrangement and had Ieyasu abducted from his entourage en route to Sumpu. Ieyasu was just six years old at the time. Nobuhide threatened to execute Ieyasu unless his father severed all ties with the Imagawa clan. Hirotada replied that sacrificing his own son would show his seriousness in his pact with the Imagawa clan. Despite this refusal, Nobuhide chose not to kill Ieyasu but instead held him for the next three years at the Manshoji Temple in Nagoya. In 1549, when Ieyasu was 7, his father Hirotada died of natural causes. At about the same time, Oda Nobuhide died during an epidemic. The deaths dealt a heavy blow to the Oda clan. An army under the command of Imagawa Sessai laid siege to the castle where Oda Nobuhiro, Nobuhide's eldest son and the new head of the Oda, was living. With the castle about to fall, Imagawa Sessai offered a deal to Oda Nobunaga (Oda Nobuhide's second son). Sessai offered to give up the siege if Ieyasu was handed over to the Imagawa clan. Nobunaga agreed and so Ieyasu (now nine) was taken as a hostage to Sumpu. Here he lived a fairly good life as hostage and potentially useful future ally of the Imagawa clan until 1556 when he was age 15.

In 1556, Ieyasu came of age, and, following tradition, changed his name to Matsudaira Jirōsaburō Motonobu (松平 次郎三郎 元信). One year later, at the age of 16 (according to East Asian age reckoning), he married his first wife and changed his name again to Matsudaira Kurandonosuke Motoyasu (松平 蔵人之介 佐元康). Allowed to return to his native Mikawa, the Imagawa ordered him to fight the Oda clan in a series of battles. Ieyasu won his first battle at the Siege of Terabe and later succeeded in delivering supplies to a border fort through a bold night attack.

In 1560 the leadership of the Oda clan had passed to the brilliant leader Oda Nobunaga. Yoshimoto, leading a large Imagawa army (perhaps 20,000 strong) then attacked the Oda clan territory. Ieyasu with his Mikawa troops captured a fort at the border and then stayed there to defend it. As a result, Ieyasu and his men were not present at the Battle of Okehazama where Yoshimoto was killed by Oda Nobunaga's surprise assault. With Yoshimoto dead, Ieyasu decided to ally with the Oda clan. A secret deal was needed because Ieyasu's wife and infant son, Nobuyasu were held hostage in Sumpu by the Imagawa clan. In 1561, Ieyasu openly broke with the Imagawa and captured the fortress of Kaminojo. Ieyasu was then able to exchange his wife and son for the wife and daughter of the ruler of Kaminojo castle. In 1563 Nobuyasu was married to Nobunaga's daughter Tokuhime.

For the next few years Ieyasu set to reform the Matsudaira clan and pacifying Mikawa. He also strengthened his key vassals by awarding them land and castles in Mikawa. They were: Honda Tadakatsu, Ishikawa Kazumasa, Koriki Kiyonaga, Hattori Hanzō, Sakai Tadatsugu, and Sakakibara Yasumasa.

Ieyasu defeated the military forces of the Mikawa Monto within Mikawa province. The Monto were a warlike group of monks that were ruling Kaga Province and had many temples elsewhere in Japan. They refused to obey Ieyasu's commands and so he went to war with them, defeating their troops and pulling down their temples. In one battle Ieyasu was nearly killed when he was struck by a bullet which did not penetrate his armor. Both Ieyasu's Mikawa troops and the Monto forces were using the new gunpowder weapons which the Portuguese had introduced to Japan just 20 years earlier.

In 1567, Ieyasu changed his name yet again, his new family name was Tokugawa and his given name was now Ieyasu. In so doing, he claimed descent from the Minamoto clan. No proof has actually been found for this claimed descent from Seiwa tennō, the 56th Emperor of Japan.

Ieyasu remained an ally of Oda Nobunaga and his Mikawa soldiers were part of Nobunaga's army which captured Kyoto in 1568. At the same time Ieyasu was expanding his own territory. He and Takeda Shingen, the head of the Takeda clan in Kai Province made an alliance for the purpose of conquering all the Imagawa territory. In 1570, Ieyasu's troops captured Tōtōmi Province while Shingen's troops captured Suruga province (including the Imagawa capital of Sumpu).

Ieyasu ended his alliance with Takeda and sheltered their former enemy, Imagawa Ujizane; he also allied with Uesugi Kenshin of the Uesugi clan — an enemy of the Takeda clan. Later that year, Ieyasu led 5,000 of his own men supporting Nobunaga at the Battle of Anegawa against the Azai and Asakura clans.

In October 1571, Takeda Shingen, now allied with the Hōjō clan, attacked the Tokugawa lands of Tōtōmi. Ieyasu asked for help from Nobunaga, who sent him some 3,000 troops. Early in 1573 the two armies met at the Battle of Mikatagahara. The Takeda army, under the expert direction of Shingen, hammered at Ieyasu's troops until they were broken. Ieyasu fled with just 5 men to a nearby castle. This was a major loss for Ieyasu, but Shingen was unable to exploit his victory because Ieyasu quickly gathered a new army and refused to fight Shingen again on the battlefield.

Fortune smiled on Ieyasu a year later when Takeda Shingen died at a siege early in 1573. Shingen was succeeded by his less capable son Takeda Katsuyori. In 1575, the Takeda army attacked Nagashino Castle in Mikawa province. Ieyasu appealed to Nobunaga for help and the result was that Nobunaga personally came at the head of his very large army (about 30,000 strong). The Oda - Tokugawa force of 38,000 won a great victory on June 28, 1575, at the Battle of Nagashino, though Takeda Katsuyori survived the battle and retreated back to Kai province. For the next seven years, Ieyasu and Katsuyori fought a series of small battles. Ieyasu's troops managed to wrest control of Suruga province away from the Takeda clan.

In 1579, Ieyasu's wife, and his eldest son, Matsudaira Nobuyasu, were accused of conspiring with Takeda Katsuyori to assassinate Nobunaga. Ieyasu's wife was executed and Nobuyasu was forced to commit seppuku. Ieyasu then named his third and favorite son, Tokugawa Hidetada, as heir, since his second son was adopted by another rising power: Toyotomi Hideyoshi, the future ruler of all Japan.

The end of the war with Takeda came in 1582 when a combined Oda - Tokugawa force attacked and conquered Kai province. Takeda Katsuyori, as well as his eldest son Takeda Nobukatsu, were defeated at the Battle of Temmokuzan and then committed seppuku.

In late 1582, Ieyasu was near Osaka and far from his own territory when he learned that Nobunaga had been assassinated by Akechi Mitsuhide. Ieyasu managed the dangerous journey back to Mikawa, avoiding Mitsuhide's troops along the way, as they were trying to find and kill him. One week after he arrived in Mikawa, Ieyasu's army marched out to take revenge on Mitsuhide. But they were too late, Hideyoshi — on his own — defeated and killed Akechi Mitsuhide at the Battle of Yamazaki. The death of Nobunaga meant that some provinces, ruled by Nobunaga's vassals, were ripe for conquest. The leader of Kai province made the mistake of killing one of Ieyasu's aides. Ieyasu promptly invaded Kai and took control. Hōjō Ujimasa, leader of the Hōjō clan responded by sending his much larger army into Shinano and then into Kai province. No battles were fought between Ieyasu's forces and the large Hōjō army and, after some negotiation, Ieyasu and the Hōjō agreed to a settlement which left Ieyasu in control of both Kai and Shinano provinces, while the Hōjō took control of Kazusa province (as well as bits of both Kai and Shinano province).

At the same time (1583) a war for rule over Japan was fought between Toyotomi Hideyoshi and Shibata Katsuie. Ieyasu did not take a side in this conflict, building on his reputation for both caution and wisdom. Hideyoshi defeated Katsuie at Battle of Shizugatake — with this victory, Hideyoshi became the single most powerful daimyo in Japan. In 1584, Ieyasu decided to support Oda Nobukatsu, the eldest son and heir of Oda Nobunaga, against Hideyoshi. This was a dangerous act and could have resulted in the annihilation of the Tokugawa. Tokugawa troops took the traditional Oda stronghold of Owari, Hideyoshi responded by sending an army into Owari. The Komaki Campaign was the only time any of the great unifiers of Japan fought each other: Hideyoshi vs. Ieyasu. In the event, Ieyasu won the only notable battle of the campaign at Nagakute. After months of fruitless marches and feints, Hideyoshi settled the war through negotiation. First he made peace with Oda Nobuo, and then he offered a truce to Ieyasu. The deal was made at the end of the year; as part of the terms Ieyasu's second son, O Gi Maru, became an adopted son of Hideyoshi. Ieyasu's aide, Ishikawa Kazumasa, chose to join the pre-eminent daimyo and so he moved to Osaka to be with Hideyoshi. However, only a few other Tokugawa retainers followed this example. Hideyoshi was understandably distrustful of Ieyasu, and five years passed before they fought as allies. The Tokugawa did not participate in Hideyoshi's successful invasions of Shikoku and Kyūshū.

In 1590 Hideyoshi attacked the last independent daimyo in Japan, Hōjō Ujimasa. The Hōjō clan ruled the eight provinces of the Kantō region in eastern Japan. Hideyoshi ordered them to submit to his authority and they refused. Ieyasu, though a friend and occasional ally of Ujimasa, joined his large force of 30,000 samurai with Hideyoshi's enormous army of some 160,000. Hideyoshi attacked several castles on the borders of the Hōjō clan with most of his army laying siege to the castle at Odawara. Hideyoshi's army captured Odawara after six months (oddly for the time period, deaths on both sides were few). During this siege, Hideyoshi offered Ieyasu a radical deal. He offered Ieyasu the eight Kantō provinces which they were about to take from the Hōjō in return for the five provinces that Ieyasu currently controlled (including Ieyasu's home province of Mikawa). Ieyasu accepted this proposal. Bowing to the overwhelming power of the Toyotomi army, the Hōjō accepted defeat, the top Hōjō leaders killed themselves and Ieyasu marched in and took control of their provinces, so ending the clan's reign of over 100 years.

Ieyasu now gave up control of his five provinces (Mikawa, Tōtōmi, Suruga, Shinano, and Kai) and moved all his soldiers and vassals to the Kantō region. He himself occupied the castle town of Edo in Kantō. This was possibly the riskiest move Ieyasu ever made — to leave his home province and rely on the uncertain loyalty of the formerly Hōjō samurai in Kantō. In the event, it worked out brilliantly for Ieyasu. He reformed the Kantō provinces, controlled and pacified the Hōjō samurai and improved the underlying economic infrastructure of the lands. Also, because Kantō was somewhat isolated from the rest of Japan, Ieyasu was able to maintain a unique level of autonomy from Hideyoshi's rule. Within a few years, Ieyasu had become the second most powerful daimyo in Japan. There is a Japanese proverb which likely refers to this event "Ieyasu won the Empire by retreating."

In 1592, Hideyoshi invaded Korea as a prelude to his plan to attack China (Japanese invasions of Korea [1592 – 1598]). The Tokugawa samurai never took part in this campaign. Early in 1593, Ieyasu was summoned to Hideyoshi's court in Nagoya (in Kyūshū, different from similarly spelled city in Owari Province), as a military advisor. He stayed there, off and on for the next five years. Despite his frequent absences, Ieyasu's sons, loyal retainers and vassals were able to control and improve Edo and the other new Tokugawa lands.

In 1593, Hideyoshi fathered a son and heir, Toyotomi Hideyori.

In 1598, with his health clearly failing, Hideyoshi called a meeting that would determine the Council of Five Elders who would be responsible for ruling on behalf of his son after his death. The five that were chosen as regents (tairō) for Hideyori were Maeda Toshiie, Mōri Terumoto, Ukita Hideie, Uesugi Kagekatsu, and Ieyasu himself, who was the most powerful of the five. This change in the pre-Sekigahara power structure became pivotal as Ieyasu turned his attention towards Kansai; and at the same time, other ambitious (albeit ultimately unrealized) plans, such as the Tokugawa initiative establishing official relations with Mexico and New Spain, continued to unfold and advance.

Hideyoshi, after three more months of increasing sickness, died on September 18, 1598. He was nominally succeeded by his young son Hideyori but as he was just five years old, real power was in the hands of the regents. Over the next two years Ieyasu made alliances with various daimyo, especially those who had no love for Hideyoshi. Happily for Ieyasu, the oldest and most respected of the regents died after just one year. With the death of Regent Maeda Toshiie in 1599, Ieyasu led an army to Fushimi and took over Osaka Castle, the residence of Hideyori. This angered the three remaining regents and plans were made on all sides for war. Opposition to Ieyasu centered around Ishida Mitsunari, a powerful daimyo but not one of the regents. Mitsunari plotted Ieyasu's death and news of this plot reached some of Ieyasu's generals. They attempted to kill Mitsunari but he fled and gained protection from none other than Ieyasu himself. It is not clear why Ieyasu protected a powerful enemy from his own men but Ieyasu was a master strategist and he may have concluded that he would be better off with Mitsunari leading the enemy army rather than one of the regents, who would have more legitimacy. Nearly all of Japan's daimyo and samurai now split into two factions — Mitsunari's group and anti-Mitsunari Group. Ieyasu supported the anti-Mitsunari Group, and formed them as his potential allies. Ieyasu's allies were the Date clan, the Mogami clan, the Satake clan and the Maeda clan. Mitsunari allied himself with the three other regents: Ukita Hideie, Mori Terumoto, and Uesugi Kagekatsu as well as many daimyo from the eastern end of Honshū.

In June 1600, Ieyasu and his allies moved their armies to defeat the Uesugi clan who was accused of planning to revolt against Toyotomi administration (Led by Ieyasu, top of Council of Five Elders). Before arriving to Uesugi's territory, Ieyasu had got information that Mitsunari and his allies moved their army against Ieyasu. Ieyasu held a meeting with daimyo, and they agreed to ally Ieyasu. He then led the majority of his army west towards Kyoto. In late summer, Ishida's forces captured Fushimi. Ieyasu and his allies marched along the Tōkaidō, while his son Hidetada went along the Nakasendō with 38,000 soldiers. A battle against Sanada Masayuki in Shinano Province delayed Hidetada's forces, and they did not arrive in time for the main battle. This battle was the biggest and likely the most important battle in Japanese history. It began on October 21, 1600 with a total of 160,000 men facing each other. The Battle of Sekigahara ended with a complete Tokugawa victory. The Western bloc was crushed and over the next few days Ishida Mitsunari and many other western nobles were captured and killed. Tokugawa Ieyasu was now the de facto ruler of Japan.

Immediately after the victory at Sekigahara, Ieyasu redistributed land to the vassals who had served him. Ieyasu left some western daimyo un-harmed, such as the Shimazu clan, but others were completely destroyed. Toyotomi Hideyori (the son of Hideyoshi) lost most of his territory which were under management of western daimyo, and he was degraded to an ordinary daimyo, not a ruler of Japan. In later years the vassals who had pledged allegiance to Ieyasu before Sekigahara became known as the fudai daimyo, while those who pledged allegiance to him after the battle (in other words, after his power was unquestioned) were known as tozama daimyo. Tozama daimyo were considered inferior to fudai daimyo.

On March 24, 1603, Tokugawa Ieyasu received the title of shogun from Emperor Go-Yozei. Ieyasu was 60 years old. He had outlasted all the other great men of his times: Nobunaga, Hideyoshi, Shingen, Kenshin. He was the shogun and he used his remaining years to create and solidify the Tokugawa shogunate (That was eventually to become the Edo period, about two hundred years under Ieyasu's Shogunate) , the third shogunal government (after the Minamoto and the Ashikaga). He claimed descent from the Minamoto clan by way of the Nitta family. Ironically Ieyasu descendants would marry into the Taira clan and Fujiwara Clans. The Tokugawa Shogunate would rule Japan for the next 250 years.

Following a well established Japanese pattern, Ieyasu abdicated his official position as shogun in 1605. His successor was his son and heir, Tokugawa Hidetada. This may have been done, in part to avoid being tied up in ceremonial duties, and in part to make it harder for his enemies to attack the real power center, and in part to secure a smoother succession of his son. The abdication of Ieyasu had no effect on the practical extent of his powers or his rule; but Hidetada nevertheless assumed a role as formal head of the bakufu bureaucracy.

Ieyasu, acting as the retired shogun (大御所 ōgosho^?), remained the effective ruler of Japan until his death. Ieyasu retired to Sunpu Castle in Sunpu, but he also supervised the building of Edo Castle, a massive construction project which lasted for the rest of Ieyasu's life. The end result was the largest castle in all of Japan, the costs for building the castle being borne by all the other daimyo, while Ieyasu reaped all the benefits. The central donjon, or tenshu, burned in the 1657 Meireki fire. Today, the Imperial Palace stands on the site of the castle.

Ogosho Ieyasu also supervised diplomatic affairs with the Netherlands and Spain. He chose to distance Japan from the Europeans starting in 1609, although the bakufu did give the Dutch exclusive trading rights and permitted them to maintain a "factory" for trading purposes. From 1605 until his death, Ieyasu consulted with an English Protestant pilot in Dutch employ, William Adams, who played a noteworthy role in forming and furthering the Shogunate's evolving relations with Spain and the Roman Catholic Church.

In 1611, Ieyasu, at the head of 50,000 men, visited Kyoto to witness the coronation of Emperor Go-Mizunoo. In Kyoto, Ieyasu ordered the remodeling of the imperial court and buildings, and forced the remaining western daimyo to sign an oath of fealty to him. In 1613, he composed the Kuge Shohatto' a document which put the court daimyo under strict supervision, leaving them as mere ceremonial figureheads. The influences of Christianity, which was beset by quarreling over the Protestant Reformation and its aftermath, on Japan were proving problematic for Ieyasu. In 1614, he signed the Christian Expulsion Edict which banned Christianity, expelled all Christians and foreigners, and banned Christians from practicing their religion. As a result, many Kirishitans (early Japanese Christians) fled to either Portuguese Macau or the Spanish Philippines.

In 1615, he prepared the Buke Shohatto, a document setting out the future of the Tokugawa regime.

The climax of Ieyasu's life was the siege of Osaka Castle (1614 – 1615). The last remaining threat to Ieyasu's rule was Hideyori, the son and rightful heir to Hideyoshi. He was now a young daimyo living in Osaka Castle. Many samurai who opposed Ieyasu rallied around Hideyori, claiming that he was the rightful ruler of Japan. Ieyasu found fault with the opening ceremony of a temple built by Hideyori — it was as if Hideyori prayed for Ieyasu's death and the ruin of Tokugawa clan. Ieyasu ordered Toyotomi to leave Osaka Castle, but those in the castle refused and started to gather samurai into the castle. Then the Tokugawa, with a huge army led by Ogosho Ieyasu and Shogun Hidetada, laid siege to Osaka castle in what is now known as "the Winter Siege of Osaka." Eventually, Tokugawa made a deal threatening Hideyori's mother, Yodogimi, firing cannons towards the castle to stop the fighting. However, as soon as the treaty was agreed upon, Tokugawa filled Osaka Castle's moats with sand so his troops could go across them. Ieyasu returned to Sumpu once, but after Toyotomi refused another order to leave Osaka, he and his allied army of 155,000 soldiers attacked Osaka Castle again in "the Summer Siege of Osaka." Finally in late 1615, Osaka Castle fell and nearly all the defenders were killed including Hideyori, his mother (Hideyoshi's widow, Yodogimi), and his infant son. His wife, Senhime (a granddaughter of Ieyasu), was sent back to Tokugawa alive. With the Toyotomi finally extinguished, no threats remained to Tokugawa's domination of Japan.

In 1616, Ieyasu died at age 73. The cause of death is thought to have been cancer or syphilis. The first Tokugawa shogun was posthumously deified with the name Tōshō Daigongen (東照大権現), the "Great Gongen, Light of the East". (A Gongen (the prefix Dai- meaning great) is believed to be a buddha who has appeared on Earth in the shape of a kami to save sentient beings). In life, Ieyasu had expressed the wish to be deified after his death in order to protect his descendants from evil. His remains were buried at the Gongens' mausoleum at Kunōzan, Kunōzan Tōshō-gū (久能山東照宮). After the first anniversary of his death, his remains were reburied at Nikkō Shrine, Nikkō Tōshō-gū (日光東照宮). His remains are still there. The mausoleum's architectural style became known as gongen-zukuri, that is gongen style.

Ieyasu had a number of qualities that enabled him to rise to power. He was both careful and bold — at the right times, and at the right places. Calculating and subtle, Ieyasu switched alliances when he thought he would benefit from the change. He allied with the Hōjō clan; then he joined Hideyoshi's army of conquest, which destroyed the Hōjō clan; and he himself took over their lands. In this he was like other daimyo of his time. This was an era of violence, sudden death, and betrayal. He was not very well liked nor personally popular, but he was feared and he was respected for his leadership and his cunning. For example, he wisely kept his soldiers out of Hideyoshi's campaign in Korea.

He was capable of great loyalty: once he allied with Oda Nobunaga, he never went against Nobunaga; and both leaders profited from their long alliance. He was known for being loyal towards his personal friends and vassals, whom he rewarded. However, he also remembered those who had wronged him in the past. It is said that Ieyasu executed a man who came into his power because he had insulted him when Ieyasu was young.

Ieyasu protected many former Takeda retainers from the wrath of Oda Nobunaga, who was known to harbor a bitter grudge towards the Takeda. He managed to successfully transform many of the retainers of the Takeda, Hōjō, and Imagawa clans — all whom he had defeated himself or helped to defeat — into loyal followers.

He had nineteen wives and concubines, by whom he had eleven sons and five daughters. The eleven sons of Ieyasu were Matsudaira Nobuyasu (松平 信康), Yūki Hideyasu (結城 秀康), Tokugawa Hidetada (徳川 秀忠), Matsudaira Tadayoshi (松平 忠吉), Takeda Nobuyoshi (武田 信吉), Matsudaira Tadateru (松平 忠輝), Matsuchiyo (松千代), Senchiyo (仙千代), Tokugawa Yoshinao (徳川 義直), Tokugawa Yorinobu (徳川 頼宣), and Tokugawa Yorifusa (徳川 頼房). (In this listing, the two sons without surnames died before adulthood.) His daughters were Kame hime (亀姫), Toku hime (徳姫), Furi hime (振姫), Matsu hime (松姫) , Eishōin hime (_姫), and Ichi hime (市 姫). He is said to have cared for his children and grandchildren, establishing three of them, Yorinobu, Yoshinao, and Yorifusa as the daimyos of Kii, Owari, and Mito provinces, respectively. At the same time, he could be ruthless when crossed. For example, he ordered the executions of his first wife and his eldest son — a son-in-law of Oda Nobunaga; Oda was also an uncle of Hidetada's wife Oeyo.

After Hidetada became shogun, he married Oeyo of the Oda clan and they had two sons, Tokugawa Iemitsu and Tokugawa Tadanaga. They also had two daughters, one of whom, Sen hime, married twice. The other daughter, Kazuko hime, married Emperor Go-Mizunoo of descent from the Fujiwara clan.

Ieyasu's favorite pastime was falconry. He regarded it as excellent training for a warrior. "When you go into the country hawking, you learn to understand the military spirit and also the hard life of the lower classes. You exercise your muscles and train your limbs. You have any amount of walking and running and become quite indifferent to heat and cold, and so you are little likely to suffer from any illness.". Ieyasu swam often; even late in his life he is reported to have swum in the moat of Edo Castle.

Later in life he took to scholarship and religion, patronizing scholars like Hayashi Razan.

He claimed that he fought, as a warrior or a general, in 90 battles.

In some sources Ieyasu is known to have the bad habit of biting his nails when nervous, especially before and during battle.

He was interested in various kenjutsu skills, was a patron of the Yagyū Shinkage-ryū school, and also had them as his personal sword instructors.

Ieyasu ruled directly as shogun or indirectly as Ogosho during the Keichō era (1596 – 1615).