The Encyclopaedia of Aikido by S. Pranin.
"The techniques of aikido derive mainly from the Daito-ryu Aikijujutsu of Sokaku Takeda. Philosophically, Ueshiba was greatly influenced by the views of Onisaburo Deguchi, leader of the Omoto Religion. The art evolved gradually during the late 1920s and 30s under various names. Its modern name was officially adopted in 1942 as a result of the reorganisation of Japanese martial arts by the Dai Nihon Butokukai. Its emergence as a major martial art and its spread outside of Japan took place after World War II." The Encyclopaedia of Aikido by S. Pranin.
"A town of some 15,000 inhabitants situated about 63 miles to the northeast of Tokyo. Location of the country home of Morihei Ueshiba who retired there during the war in 1942. Site of Aiki Shrine built by the founder as the spiritual center of Aikido. Due to the post-war ban on martial arts by General Headquarters of the Allied Forces and the fact that a number of bombed-out families lived in the Tokyo dojo, the Aikikai Hombu Dojo was moved to Iwama in 1948 through c. 1956 when it was returned to Tokyo. Ueshiba's dojo is attached to his home and had been under the care and direction of Morihiro Saito since the former's death in 1969. Site of annual Taisai ceremony which commemorates the death of the founder held on April 29 (to coincide with the late Showa Emperor's birthday, a public holiday), although the founder actually died on April 26." The Encyclopaedia of Aikido by S. Pranin.