Toyotomi Hideyoshi (1536-1598) was a Japanese samurai and lord during the Sengoku period, who rose from a peasant in his earlier life, to becoming one of the most important figures in Japanese history.
Often known as the second (of three) 'uniters' of Japan, his military prowess, cunning and tenacity was largely responsible for bringing Japan together, after decades of civil war and bloodshed between neighbouring states.
Influence: Class-Setter and Castle-Builder
Today, Hideyoshi is known and remembered in Japan through his history, as well as various physical monuments - most notably having built Osaka Castle (below), issued the construction for many temples in Kyoto, as well as his own castle -- Momoyama castle.
He was also influential in establishing the class system of the time (with the emperor at the top of society, followed by nobles, shogun, daimyo (lords), samurai, peasants, craftsmen, and merchants at the bottom), and instituting restrictions on weapons for the samurai which had a lasting effect on them
Rise to Prominence: Skilled Negotiator and Clan Recruiter
It's widely believed that Hideyoshi served under another famous Japanese warlord, Oda Nobunaga. He acted in various roles, and was known as a powerful and skilled negotiator, in addition to overseeing and carrying out repairs to numerous castles and temples. His negotiating powers helped him convert many members of rival clans, to his own (under Nobunaga), which further elevated his status.
Hideyoshi quickly became one of Nobunaga's most important generals, leading the clan to several victories, and was then made lord of several districts as reward. When Nobunaga died in 1582, Hideyoshi took it upon himself to avenge is former lord's death. He accomplished this two weeks later at the battle of Yamazaki, subsequently ascending Nobunaga as the leader of the clan.
Between 1585 and 1592, Hideyoshi launched a series of attacks (around 7 of them) upon different regions of Japan, ultimately conquering them all with his large and skilled army, effectively uniting the warring provinces into one unified country.
As the provinces had been split for decades, there was much resistance to being conquered, but ultimately Hideyoshi's armies succeeded in pacifying the various leaders, either through surrender or through takeover and executions. Thus, Japan was unified under his rule.
In around 1582, in an effort to consolidate power, Toyotomi commissioned a so-called Sword hunt, which required all society members to hand over their weapons, or face a penalty of death. This meant that any samurai normally working as farmers, had to choose between being a true soldier, or a farmer, rather than being both at the same time.
Korean Campaign: Hideyoshi's Downfall
Known earlier in life for his caution and adept negotiation skills, it is said that Toyotomi became ruthless and cruel later in his life, devoting more effort to consolidating power and strengthening his leadership.
With this in mind, in the 1590s he initiated an attack on Ming China through Korea. A samurai army of over 100,000 troops devastated parts of Korea during this attack, with victims counted by their chopped-off noses and brought back to Japan as evidence. This campaign proved unsuccessful in the end, with Japan's entire navy having been destroyed and the casualties in the thousands.
In September 1598, Toyotomi died, leaving behind a young infant son. After his passing, several of his top generals and nobles jostled over power (since his son was too young to lead), which ultimately led to infighting and the loss of the power the clan once held.