For starters, Kendo was not created by a single person, nor by a group, nor was it created immediately out of nothing. In a way, Kendo has a unique history in that it was created from ideals and values that already existed within Japan's rich history...
Ever since the introduction of the sword from the mainland, various schools were erected in Japan teaching Kenjustsu (translated as "art of the sword") to the samurai (bushi) classes. Headed by leading swordsmen, each school taught a unique style to its students.
At first, the schools taught ryu (swordsmanship) in response to the civil wars that plagued Japan. But over time, as the country entered a period of relative stability and peace, the schools shifted their teachings over to the Kenjutsu's spiritual and mental aspects, focusing more on honor and personal refinement. This shift became more important by the 16th century, when Japan was finally unified under the Tokugawa Shogunate.
Now that peace and stability was permanent, Kenjutsu became somewhat less useful in terms of warfare. As a result, the school sought ways to continue teaching the art under new conditions. By around the 1700s, instead of their swords, students and teachers alike practiced using bamboo swords called shinais. A century later, equipment similar to the modern-day bogu were implemented to lessen injuries.
This in a way was significant because it enabled students and teachers to learn without fatalities or serious injuries. It also enable schools to improve their unique styles as well as discover new ones.
Unfortunately, once the Tokugawa Shogunate collapsed in the 19th century, the Meiji government disbanded the samurai, forcing Kenjutsu to fall into decline. But in 1877, a rebellion broke out which the police managed to suppress. This event was crucial because several of the police officers in the raid actually were taught Kenjutsu. Seeing its usefulness, the Meiji government reevaluated it, and made it a requirement for not only the police, but for schools as well. However, due to its rising popularity, there grew a need for make it universal in form.
By 1912, after meeting with several teachers from various Kenjutsu schools, a consensus was made on a system that would be recognized by all. Instead of a form that focuses on defeating the opponent (which was what Kenjutsu was all about), this form, called Kendo, would focus more on self-improvement. This became popular in universities and schools, where it became mandatory for students.
Unfortunately, Kendo went into decline after World War II, as the Allied Powers during the Occupation banned the practice. Luckily, by 1948 the ban was lifted, and supporters of the sport immediately restored it to popularity. By 1957, Kendo became one of Japan's national pastimes, and at the same year, the All Japan Kendo Federation was created. Shortly after its creation, the International Kendo Federation followed in 1971, which made Kendo not only popular in Japan, but around the world as well.
Images courtesy of Charles Goodin