Bo Mya was among a significant number of Karens who joined the British — specifically in Bo Mya's case, Force 136 — during World War II, with whom he fought the Japanese from the East Dawna hills in 1944 to 1945.
Based at Manerplaw ("victory field") close to the Thai-Burma border, the KNU under his control, and its military wing the Karen National Liberation Army (KNLA), was probably the most successful of the ethnic rebel organisations fighting Rangoon in the Karen Conflict in the 1970s and 1980s.
A devout Christian of the Seventh-day Adventist Church, Bo Mya had always risked antagonising elements from within the predominantly Karen Buddhist and animist KNLA ranks.
This was demonstrated at the beginning of 2004 when Bo Mya travelled to Yangon (Rangoon), his first visit to the capital in 50 years, to hold peace talks with Khin Nyunt, who was Prime Minister at the time.
On 24 December 2006, Bo Mya died in a hospital in Mae Sot, Thailand, near the eastern border of Myanmar.