The strategies of both sides had changed from their original versions as the battles progressed.
Nationalist strategy After the destruction of the entire 72nd Reorganized Division in late April 1947 in the
Tai'an-Mengyin Campaign, the nationalists became very cautious and concentrated their forces in their movements afterward. On May 4, 1947, the communist high command radioed the East China Field Army that since it was impossible to fight large nationalist formations because the nationalists had concentrated their forces, the current tactic of waiting for an appropriate opportunity was to be maintained As long as they were patient, there would always be the opportunity to annihilate the enemy. Two days later the communist high command once again radioed the
East China Field Army to instruct local communists on several important points: Never be impatient and never separate the concentrated forces, because as long as the concentrated force are ready to be mobilized, there would always be the opportunity to destroy the enemy. Local communist commanders redeployed their forces in early May 1947 by withdrawing their main force eastward to the region east of
Laiwu and
Xintai, while the communist 2nd and 7th Columns, originally planned to be deployed to central China, were instead withdrawn to
Ju (莒) County, and the communist 6th Column was withdrawn to Pingyi (平邑) in southern
Shandong. The communists were waiting to ambush the nationalists at the proper moment. Nationalist commander Gen.
Chiang Kai-shek had erroneously believed that the communist retreat was a sign of weakness and that they were no longer able to fight any decisive battles, so on May 10 he gave the order to pursue and eradicate them. Gen.
Gu Zhutong subsequently ordered the three nationalist corps under his command to give chase toward
Boshan and Yishui. Gen.
Tang Enbo, the
commander-in-chief of the nationalist I Corps at the right flank, abandoned the previously proven tactics of prudently pushing the enemy and acted on his own without coordinating with the II Corps and III Corps; he ordered the 74th Reorganized Division to advance toward Tanbu on May 11 from Tao Xu (桃墟) and Duo (垛) Village in an attempt to take control of the region along the highway from Yishui to Mengyin (蒙阴). To protect his flanks, he ordered the 7th Army and 48th Reorganized Division to advance toward Yishui in the north, and the nationalist 65th Reorganized Division to guard Mengyin. The resulting advance dangerously overexposed the nationalist units.
Communist strategy On May 11 the communists learned that the nationalist 5th Army and 48th Reorganized Division had taken regions including Mia Family's Bent (Miao Jia Qu, 苗家曲) and Border Lake (Jie Hu, 界湖) by venturing out from Riverine Sunny and was advancing toward Yishui, leaving them dangerously exposed. The communists decided to ambush these units and, if possible, also any reinforcing units. After the order was given, new intelligence revealed Tang Enbo's plan and that the nationalist 74th Reorganized Division was advancing toward Tanbu. Communist commanders of the
East China Field Army analyzed the situation and decided that it would be better to first annihilate the 74th Reorganized Division because it was the most dangerously exposed, and the gap between it and other nationalist units were the largest, making it easier to surround and destroy it. The commander of the nationalist 74th Reorganized Division, Gen. Zhang Lingfu, was regarded by many other nationalist commanders as arrogant because he was a favorite of Chiang Kai-shek and so was not on good terms with them, especially with Li Tianxia, the commander of the 83rd Reorganized Division. His relationship with his direct superior Tang Enbo was also quite rocky, so the communists believed that if Lingfu's 74th Reorganized Division was under attack, other nationalist commanders would not be too enthusiastic about saving it. The rugged terrain would limit the mobility of the mechanized nationalist force, while the communists could take advantage of it to hide and move their troops. The 74th Reorganized Division was one of the top five crack units of the nationalist forces, and once it was completely destroyed it would be a huge psychological blow to the nationalist morale and good propaganda for the communists. Another reason they had for destroying Lingfu's forces was personal: he had openly and often proclaimed that his goal was to feed Communist commander
Chen Yi "to the fishes by driving he and his followers into the East China Sea. The communists were therefore determined to destroy their nemesis. After the communists had changed their mind on their targets, the communists ordered a redeployment of their forces on the morning of May 12: they would concentrate at least five columns (armies) to destroy the 74th Reorganized Division in the region bordered by the
Menglianggu (孟良崮) Mountains in the north and Tanbu in the south. Communist forces on their eastward march were ordered to immediately march in the opposite direction to the east of Mengyin. The Communist 1st, 4th, 6th, 8th, 9th and the Specialized Columns (armies) were assigned to attack the 74th Reorganized Division, while the communist 2nd, 3rd, 7th, 10th Columns (armies) and local militias were to prevent nationalist units, including the 5th and 7th Army and 11th, 25th, 48th, 65th and 83rd Reorganized Divisions from reinforcing the 74th Reorganized Division by blocking them in the regions of
Xintai,
Laiwu,
Linyi, Lintai (临泰) and Riverine Sunny regions. ==74th Reorganized Division besieged==