In 1942, he decided to start Tang Soo Do or Chung Do Kwan style training (School of the Blue Wave) under Lee Won-kuk, who was just returning from Japan, as Son would later remember.
[3] At the end of World War II in 1945, Korea saw military, political and social conflicts that forced Lee Won-kuk to move to Japan in 1951.
During the Korean War, Son took over the leadership of Chung Do Kwan, gathered school members, and kept teaching and promoting the style through tournaments, exhibitions and press articles.
Korean President Syngman Rhee named Son chief instructor of the Republic of Korea Army, where he met Choi Hong-hi, major general of the 29th Infantry Division.
He recruited a group of 50 military staff, some of whom were high-ranking students from Chung Do Kwan like professional soldiers (Hyun Jong-myun, Nam Tae-hi, Han Cha-kyo, Woo Jong-rim, Ko Jae-chun, Kim Suk-kyu, and Kwak Kuen-suk.
On June 16, 1959, Son, worried about keeping the philosophical principles of Chung Do Kwan, published a letter in the South Korean newspaper Seoul Shinmun dismissing a group of advanced students including Choi, Nam and Uhm.
Choi was elected president due to his position as a general in the Republic of Korea Army when the country was under a military regime and for the promise he made to other school chiefs to promote taekwondo.
The organization grew fast and in 1965, a group of Korean instructors, some of them ex-students of Son in Korea, established themselves in the U.S. Their first black belts started to promote the martial art in the U.S.
In 1969, Luke Grande arrived in Venezuela and founded the first taekwondo Chung Do Kwan school in that country and in 1987, Rod Preble did the same in Australia.
The first 11 black belts promoted by Son in North America were: As Luke Grande said: "In the first years of his arrival to the USA, the training was very intense.
We ran in Central Park and then kick a tree at least 100 times with each leg; in rain or snow, with the intense heat of the summer, the training never stopped.