In the documentary on the Sino-Vietnam War of 1979, you can see China sending many divisions of troops into Vietnam. Most of the time, the Chinese troops were unopposed as they kept moving deeper into Vietnam. At 2:00 into the video, a Chinese heavy howitzer barrage is underway. At 2:40 into the video, Chinese MLRS obliterate enemy positions. At 7:04 into the video, you see standard Chinese military tactics. A heavy artillery barrage is followed by MLRS rocket attacks. Next, the tanks break through the enemy defenses. At 9:45 into the video, a Chinese tank barrage levels the top of a mountain. At 18:03 into the video, Chinese flamethrowers are used to flush out Vietnamese troops. China possessed all of the heavy weaponry. The Vietnamese could not stop the invading Chinese army and had to keep retreating. It didn't matter, because China pounded the Vietnamese army with Chinese heavy howitzers, MLRS, and main tank guns whenever there was a battle. The Vietnamese were on the receiving end of the Chinese heavy weaponry and the Vietnamese suffered heavy losses. China rolled through one Vietnamese village after another. China burned a few down to teach the Vietnamese a lesson. China thoroughly dominated the Vietnamese and decided to go home. The alternative was to burn all of Vietnam down. That was not the decision of the Chinese leadership. Watch the video and see the Chinese heavy weaponry domination. A few years ago, I read the logs of a Chinese artillery officer. That army group fired heavy artillery shells for hours at a mountain during one afternoon. China killed about 3,500 elite Vietnamese troops that afternoon. China resupplied the Chinese artillery group by transporting a new shipment of 150 train-cars of artillery shells. The simple fact is that Vietnam was pounded by a staggering number of Chinese artillery shells throughout the entire war. ---------- At 24:38 into the video, you can see that China was within striking distance of Hanoi (e.g. the big red dot on the map). At this point, the Chinese PLA army received instructions from the Chinese central government to halt its offensive. Vietnam could never stop the Chinese PLA army. It was the order from the Chinese central leadership that stopped the Chinese offensive.