When it comes to the "Volunteer Army", you may think of the 38th Army of "Long live", the 20th Army and the 27th Army of the bloody battle of Changjin Lake, and the 50th Army that was the first to attack Seoul. These heroic and glorious troops fought for the honor of the country and the nation in a foreign land, and played a great military prestige with iron-blooded achievements, leaving the most colorful mark in military history. But you may not know that in 1965, there was also a special "volunteer army", who were also ordered to go out to fight at the call of the state. They wore helmet-shaped hats and green canvas uniforms, with no rank and no collar badge cockade. Their exploits are no less great, but their names are unknown. 320,000 soldiers went out of southern Xinjiang to fight a bloody war for eight years, and they are the strongest pillars of the country. 
In the spring of 1965, Le Duan and Vo Nguyen Gia were entrusted by Ho Chi Minh to lead a delegation to Beijing, asking China to expand its aid to Vietnam and send "volunteers" to Vietnam to support. Like the Korean War, after the success of Vietnam's resistance to France in the 50s, the U.S. military could not wait to intervene in Southeast Asia, wanting to prop up the puppet regime of South Vietnam and attack North Vietnam, which was ideologically opposed to it. In the early 60s, the US military launched the so-called "special war" and the "Gulf of Tonkin incident" one after another, and then openly sent the Air Force and Marine Corps into Vietnam to participate in the war, provoking an all-out war in which the south fought and the north bombed. 
At the same time, US warplanes have also continuously intruded into the airspace over Hainan Island and Yunnan and Guangxi, killing and wounding Chinese sailors and PLA soldiers. In the face of imperialist ambitions and the huge threat to China's homeland security, ** decided not to compromise again, officially issued the order of "resisting US aggression and aiding Vietnam", and sent the People's Liberation Army to fight in Vietnam. However, in view of the experience of the Korean War, if China directly entered the war, the sacrifice would be too great, and it would risk a head-on war with the United States, which was something that the new China, which was in the initial stage of economic development at that time, should try its best to avoid. Therefore, in the form of sending troops, the PLA borrowed the model of the Soviet Union when it supported North Korea and the PLA resisted France and aided Vietnam, that is, sending troops to indirectly participate in the war and conduct a covert war. To put it simply, the North Vietnamese troops put up frontal resistance, while the PLA is responsible for military defense and strategic, tactical, and material support in the rear. 
If the PLA's bottom line for the Korean War was the "38th parallel," then the bottom line of the Vietnam War was the "17th parallel." Preventing the US aggressors from entering North Vietnam and preventing a man-eating tiger from appearing on the side of the couch of New China is precisely the historical mission of the PLA soldiers to go out of southern Xinjiang. Peace is always something we need to strive for. On June 9, 1965, the second detachment of the Volunteer Army Engineering Corps entered Vietnam as the first batch of troops to participate in the war under the leadership of Major General Zeng Xuqing, deputy political commissar of the 23rd Army, and was responsible for the emergency construction of fortification projects, submarine cable projects, and communication line projects on islands and coastal areas in northeast Vietnam, which also announced the official opening of the prelude to resisting US aggression and aiding Vietnam. 
On August 1, the 61st Detachment of the Antiaircraft Artillery Unit of the Chinese People's Volunteers (61st Army Antiaircraft Artillery Division Detachment (63rd Army Antiaircraft Artillery Division) entered Vietnam from Yunnan and Guangxi to participate in the war, stationed on the line from Lao Cai and Lang Son to Friendship Pass, and guarded the important transportation hub in northern Vietnam. For the People's Liberation Army at that time, the antiaircraft artillery was a treasure in the palm of the hand, and this unit only really entered the development of regular units after the founding of the People's Republic of China. In the War to Resist US Aggression and Aid Korea, the antiaircraft artillery and fighter aviation units of the Chinese People's Volunteers fought in concert, destroying 2,335 enemy planes and damaging 7,527 enemy planes, effectively supporting the combat operations of the main force of the army. In the subsequent territorial air defense operations, the antiaircraft artillery unit shot down 89 US and Kuomintang air force planes that were conducting reconnaissance and harassment on the mainland, thus making the first contribution to national defense. 
In this War to Resist US Aggression and Aid Vietnam, the antiaircraft artillery unit is also the core combat strength of the Chinese People's Volunteers. Many people blame the victory in the Vietnam War on the pristine jungles of Southeast Asia, believing that it was this natural umbrella that made the US fighter planes useless scrap metal, so that the 864,000 tons of bombs could not find any targets. But we should also know that in the later stage of the Vietnam War, 1,707 US fighters were shot down and 1,608 were damaged. Without this Dinghai Divine Needle in the rear, there would not have been a moment of peace in the airspace north of Vietnam. During the three years and nine months of air defense operations in the Vietnam Aid War, the Volunteers sent a total of 16 antiaircraft artillery detachments with a total of 150,000 people, including 9 divisions, 38 regiments, and more than 80 independent battalions of the ArmySeven divisions, 26 regiments, 8 independent battalions, 9 searchlight battalions, 14 radar companies, and 2 formed regiments of the Air Force and the Navy's antiaircraft artillery were also attached to the battle. In this foreign battlefield, one of the sharpest swords of the new China has undergone the most severe test, and the four-year round of warfare has also sharpened countless combat heroes and military elites. For our fighters, actual combat is always the best training ground. 
In addition to combat units, the Chinese People's Volunteers also dispatched railway and highway engineering construction units and logistical support units, as well as communications engineering brigades, mine-clearing work brigades, shipping brigades, and ground-to-air missile expert groups. Perhaps in most people's subconscious, these engineering and logistics units are far less heroic than combat units, because their work is relatively quieter and safer, but in fact, this is the biggest misunderstanding. In modern warfare, the rear forces are also the most critical link. For example, during the period of aiding Vietnam, the mine-sweeping work brigade was formed on the basis of the South China Sea Fleet, with 12 mine-sweeping boats and 4 support boats, totaling more than 300 people, and its main task was to clear the mines in the waterways of Haiphong and Hongji ports. This kind of work seems to be leisurely, but it is the most cutting-edge, and the requirements for equipment and technical personnel are extremely high. Without the escort of the South China Sea Fleet, the volunteers and North Vietnamese soldiers would face a dead sea and a direct attack from the US ** boats, which is very deadly. 
Similarly, the task of building roads undertaken by the engineering troops was carried out under extremely difficult conditions. 1,206 kilometers of roads, 305 bridges with a total length of 6,854 meters, 4,441 culverts with a total length of 46,938 meters, and 30.5 million cubic meters of earth and stone have been completed. As Ho Chi Minh praised: "Although you have only built more than 1,200 kilometers of roads for Vietnam, your friendship is better than thousands of kilometers or tens of thousands of kilometers!""The War to Resist US Aggression and Aid Korea and the War to Resist US Aggression and Aid Vietnam are equally great victories, and these are two moves by the Chinese people to change the world pattern. Without the bloody struggle of hundreds of thousands of volunteers, there would have been no hard-won peace. However, unlike the War to Resist US Aggression and Aid Korea, the War to Resist US Aggression and Aid Vietnam was a war sealed in the long river of history, and there were too few people who knew and understood it. A Forgotten War, a Group of Forgotten Heroes In July 1970, the volunteers were all evacuated and returned home after completing the tasks set for the first stage. From May 1972 to August 1973, the Automobile Unit of the Chinese People's Volunteers and the Naval Minesweeping Team once again entered Vietnam to carry out their duties, and achieved significant results. It took 8 years to resist US aggression and aid Vietnam, with a total of 320,000 volunteers involved in the war, and 1,440 soldiers died on foreign lands. Because of its concern for the impact of international relations and its refusal to create fearless diplomatic disputes, the PLA's War to Resist US Aggression and Aid Vietnam was a secret that "could not be made public" for a long time. It was not until November 20, 1979 that such a paragraph appeared in Chinese newspapers for the first time: "During Vietnam's struggle to resist US aggression and save the country, China sent more than 320,000 support troops to Vietnam in the fields of air defense, engineering, railway, and logistics support. ”
This is a glorious history that has been sealed for 15 years. The War to Resist US Aggression and Aid Vietnam was not as vigorous as the War to Resist US Aggression and Aid Korea, nor was there the success of the First World War of the counterattack against India, nor the thunderous victory of the counterattack against Vietnam. Because of the particularity of the background of the times, this eight-year war is not well known to some people, and those volunteer soldiers who defended their homes and countries in foreign land did not leave too much glory and glory. But the characteristics of the best people are like this, they have a country in their hearts, they are fearless of life and death, they are meaningless in fame and fortune, and heroes are willing to be silent.