Although the Polibureu made the decision to send PVA to Korea on Oct.8, PRC delayed the invasion due to more debates on whether to act alone without Soviet support. Major PVA forces did not enter Korea until the night of Oct. 16 1950, when a unit of 42d army of the 13th Army Group crossed Yalu. On Oct. 18, Chairman Mao issued the final order for four PVA armies and 3 artillery divisions to enter Korea on Oct. 19.
An army in PLA was like the Corps in American infantry. A PLA army consists of 3 divisions of about 10,000 men each, however, actual division strength was usually 7000-8500 .
Notice that a PLA division is less than half the authorized strength of a US division. A PLA division has three 3000-men regiments. A US division consisted of three regiments of infantry, three battalions of 105mm artillery, 1 battalion of 155mm artillery, an anti-aircraft battalion, a tank battalion and other supporting units, totalling 20,000 men.
A PLA army group is like a US Army (such as the Eighth Army), which consisted of several PLA armies. For example, the 13th Army Group consisted of 38th, 39th, 40th, 42d armies.
Today, the basic PLA ground combat unit is an Integrated Group Army, which consists of divisions of armor, mechanized infantry, artillery, aviation, air defense, tactical SSMs and other units, forming a formidable force of 70,000 men.
PLA was basically a rifle infantry with almost no heavy weapons beyond mortars, their rifles were mostly captured from Japanese and KMT armies in the anti-Japanese war and the civil war, and they lacked ammunition. When the Korean war started, PRC was less than one year old, and it was focusing on reconstruction of a nation which suffered 8 years of Japanese aggression and plundering. China's steel production was a meager 0.6 million tons (in comparison, US figure was 87 million tons). China had almost no industry, it could not make weapons at large quantity, especially heavy weapons and their ammunitions. A PLA army then had less than 10% of the fire power of a US Corps, it had only 36 artillery pieces of 76mm or larger, while a US Corps had over 300 guns of 105mm or larger, PLA army had no tanks. PLA also lacked transport, a PLA division had only scores of trucks, and its supply had to be carried by porters.
After PLA's first successful campaigns in Korea, PLA bought Soviet weapons enough to equip 20 divisions, thus improved its fire power. At the final stage of the war, PLA was able to mass up a good number of heavy artillery to break an ROK/US defense line by brute force.
PVA's tactics were designed to void UN's advantage of air power and artillery.
PVA used night fighting tactics. It would start an attack when night fell, withdrew and went to cover at dawn, so US airplanes could not harass them. It also used close combat, threw its units into enemy line, so the enemy artillery could not operate. Another PVA tactics was to infiltrate deep into enemy positions, attack their command posts and artillery positions directly from inside.
During the truce talks, PVA invented the bunker war, they would dug very long and deep bunkers in the hills and stock supplies there, when enemy shell the hills, they would withdraw into the bunkers, when the shelling stopped, they came out to fire on the attackers, after the surface positions taken by enemy, they would withdraw back into the bunkers, then PVA artillery would shell the enemy on the surface and they came out the bunkers again to assist the retaking of the hill.
PVA's main strategy at the beginning was the so-called "movement war", the main objective was to divide the enemy into isolated pieces and then use superior strength of force to annihilate the encircled enemy piecemeal before enemy reinforcement could be brought in, to do this, PVA uses frontal attacks and simultaneous penetrations to cut directly into enemy rear, cutoff MSR (main supply route) and withdraw routes, trap enemy units when they tried to redeploy.
To understand PLA strategies, one must study the grand campaigns in which PLA wiped out 8 million KMT troops in 2 years, with small casualty of its own.
Marshal Peng Dehuai was assigned to command the PVA on Oct. 8 1950 and he remained at that position until the end of the war.
Many US books, even those published in 1980s, claimed that the PVA commander was Lin Biao, the former commander of the Fourth Field Army to which the 13th Army Group belonged. Such claims showed complete lack of intelligence in the west. Some western source (such as the Korean War Almanac by H. G. Summers, Jr) tried to argue that because Lin Biao was regarded as a traitor in China, "the truth may never be known". The obvious flaw in such argument was that Lin Biao was the man only second to Mao until 1970, if he was the hero in Korea, there would have been huge propaganda for this official heir to Mao, yet everyone in China knew that Peng (who was out of power since 1959 ) was the man who led PVA to victory. The fact was, Mao asked Lin Biao to command the PVA, but the latter was concerned about the American fire power and refused, with scarce support from his generals, Mao had to summon Peng Dehuai back from Northwest region to ask him to take the job, Peng agreed with Mao's view on the Korean situation and took the task of commanding the PVA.