Morihei Ueshiba was born in Tanabe in the modern-day Wakayama Prefecture of Japan on 14th December 1883. His interest in martial arts stemmed from witnessing his father being beaten by ruffians, which affected him deeply. He overcame his small physical stature and poor health as a child to become an accomplished student of Daito-Ryu Aiki-Jutsu under Master Sokaku Takeda. He was also a deeply spiritual man who opposed the use of martial arts for destructive purposes. By the early 1930s, he had established his own school and style, which later came to be known as Aikido: the way of harmonising energy. On account of his great prowess as a martial artist and a teacher, he was (and still is) referred to as O-Sensei, which simply means "great teacher".

O-Sensei found all warfare abhorrent, and was particularly sickened by the senseless destruction of the Second World War. Transformed by a vision that he experienced in 1942, at the height of the fighting, he set about developing Aikido as a means to heal the illnesses of the modern world by reconnecting people with the true meaning of Bushido (the Code of the Samurai): a tireless devotion to all life, everywhere.

"The Way of the Warrior has been misunderstood as a means to kill and destroy others. Those who seek competition are making a grave mistake. To smash, injure, or destroy is the worst sin a human being can commit. The real Way of a Warrior is to prevent slaughter: it is the Art of Peace, the power of love."

Originally, Aikido had been an art taught only to a select few, usually those who were already skilled in other martial arts, and was certainly not taught to non-Japanese persons. In the years following World War II, O-Sensei opened the art to all, convinced that "everyone has a spirit that can be refined, a body that can be trained in some manner, a suitable path to follow". In due course, O-Sensei dispatched his apprentices (among them Chiba Sensei) to spread Aikido around the globe, telling them, "One day, this Art will be practiced by people all over the world!"

Even as his health grew frail with advanced age, O-Sensei continued to train and remained committed to Aikido and the vision of a better world through the practice of the Art of Peace. He passed away on 26th April 1969, and was succeeded by his son, Kisshomaru Ueshiba Sensei, who took the title Doshu: "way master", personal heir to the Founder as head of the Art. Kisshomaru Ueshiba Sensei passed away in 1999, and the founder's grandson, Moriteru Ueshiba Sensei, took the title of Doshu.