Chae Myung-shin was born on 27 November 1926, in Koksan County, to a father who was an anti-Japanese activist and a devout Christian mother, and grew up as a native believer.

His father was imprisoned and was released shortly after independence of Korea in 1945, but died in early December 1945 due to the aftereffects of torture, and his mother worked as a member of the church.

Afterwards, he taught at Jinnampo Elementary School, but following the Soviet occupation of the northern part of Korean Peninsula, Chae met Kim Il Sung, North Korea’s founder, at the opening ceremony of the Pyongyang Institute, a military and political academy.

In his nine months in the Defense Academy, he was the top performer in his class, and scored the 26th position out of the 400 students, at the time of graduation.

At that time, the communist partisans were engaged in guerrilla warfare in the mountainous regions of Gangwon Province and Gyeongbuk.

The unit infiltrated into North Korea to accomplish a special mission and rendered distinguished military services.

[6] After being promoted to major general in 1963, he served as deputy chief of the combat staff in the army headquarters.

In April 1965, Chae was summoned to the Blue House to meet with Park Chung Hee, in order to discuss opinions regarding the dispatch of combat troops to Vietnam.

[7] However, President Park Chung Hee wanted to send troops to Vietnam due to the economic and military advantages it would give Korea as Korea had offered to send troops to Vietnam earlier but was rejected until eventually, the offer was accepted by the United States.

With the need for diplomacy, Park Chung Hee decided to use the South Korean military forces to enter Vietnam to participate in the war.

[9] Chae's harsh policy caused a serious disagreement with William Westmoreland, the chief of staff of the United States Forces.

[11] However, an investigation conducted by Colonel Robert Morehead Cook of the U.S. Army Inspector General's office, published a report that pointed out that the culprits were the Blue Dragon Division of the South Korean Marine Corps.

After that, Chae disagreed with Park regarding his attempts to consolidate his power further and expressed his opposition several times, especially after the approval of the Yushin Constitution, to expand the president’s term and control.

On 1 June 1972, he left from his final position as commander of the 2nd Field Army, and retired from military service at the rank of lieutenant general.

In accordance to his wishes, he was buried next to the soldiers who died during the Vietnam War at Seoul National Cemetery.

[17] Chae was married to Moon Jeong-in, who was born to a wealthy family in North Gyeongsang Province and a graduate of Ewha Womans University.