Heshui Campaign (), consisted of several fierce battles fought between the communists and the nationalist Ma clique's force, which consisted mostly of cavalry. The campaign was fought in the post-World War II era in the eastern Gansu province in northwestern China during the Chinese Civil War, and it was one of the few conflicts from which the nationalists emerged as the victor.
Prelude After the Panlong Campaign, the communist force under the command of Peng Dehuai in northwest China had scored three consecutive victories against its nationalist adversary, and had forced the nationalists in northwestern China to cease further offensives. Both sides took rest and the communists held a celebration in the Ansai () region during this break. Zhou Enlai personally went to join the celebration on Mao Zedong's behalf and suggested that Peng's force should take the opportunity to take a much-needed break while the nationalists were resting, but Peng Dehuai disagreed because the Ansai region was a very poor region lacking any resources and thus could not support his large army numbering in the tens of thousands. Instead, Peng Dehuai suggested that his force should strike toward eastern Gansu while the local nationalist force under the command of Hu Zongnan was resting, so that the communists could replenish themselves in the newly conquered area in eastern Gansu. When Peng's suggestion was finally telegraphed to Mao Zedong on May 14, 1947, Mao replied the same day and agreed. Peng Dehuai also hoped that taking eastern Gansu would force the Ma clique to redeploy its forces and thus provide an opportunity for another communist victory, as he and Xi Zhongxun had told Mao in their telegraph on May 28.
On May 21, 1947, the communists started their push toward eastern Gansu, in three fronts from the Ansai region under the personal command of Peng Dehuai: the communist 1st Column was at the right, and the Newly Organized 4th Brigade was at the center, while the 2nd Column under the command of Wang Zhen was on the left. The town of Heshui () which was in nationalist hands was selected as the primary target due to the region originally being an area of active communist guerrilla activities before World War II as well as being the place where Mao Zedong's force met with local Chinese Red Army commanded by Xie Zichang () and Liu Zhidan () at the end of the Long March. During World War II, the region was granted by the nationalist government of Chiang Kai-shek to the communists as their area of control, so that the communists were legally allowed to station the 358th Brigade of the Eighth Route Army under the command of Wang Hongqian () in the region and turn it into a communist base. The communist 358th Brigade was headquartered at Qingyang () while the 770th Regiment under the command of Zhang Caiqian () was stationed at Heshui. It was only after World War II, that the nationalists were able to retake the region from the communists.
First stage After the 48th Brigade of the nationalist Reorganized 17th Division was annihilated by the enemy in the Battle of Xihuachi, the nationalists lacked sufficient troops to fill the new gaps in their defense. As a result, the remaining nationalist garrison was gravely overstretched and the nationalist northern flank was dangerously exposed. In order to boost local defense, the nationalist Reorganized 82nd Division was deployed to Pingliang in eastern Gansu in early 1947. To strengthen the defense of the triangular region bordered by regions of Western Peak (Xi Feng, ), Ning ) County, and Zhenyuan (), the Reorganized 8th Cavalry Brigade (without its Heavy Weaponry Battalion and its 1st Regiment) of the nationalist Reorganized 82nd Division was deployed to Qingyang. The 1st Regiment of the Reorganized 8th Cavalry Brigade of the nationalist Reorganized 82nd Division was deployed to Red City (Chi Cheng, ), southeast of Qingyang. The Heavy Weaponry Battalion of the Reorganized 8th Cavalry Brigade of the nationalist Reorganized 82nd Division was tasked to defend Heshui with the help of the Gansu 2nd Security Regiment. The Independent 5th Cavalry Regiment of the nationalist Reorganized 82nd Division was deployed to Zhengning (). The 1st Regiment of the Reorganized 100th Brigade of the nationalist Reorganized 82nd Division was deployed to Ning County, and the 2nd Regiment of the Reorganized 100th Brigade of the nationalist Reorganized 82nd Division was deployed to the town of Early Victory (Zao Sheng, ), and the 3rd Regiment of the Reorganized 100th Brigade of the nationalist Reorganized 82nd Division was deployed to the town of Zhenyuan. Qinghai 1st Security Cavalry Regiment was deployed to Jingchuan (), while Qinghai 2nd Security Cavalry Regiment was tasked to defend Pingliang with the help of 2nd Company of the 2nd Regiment of the Reorganized 8th Cavalry Brigade of the nationalist Reorganized 82nd Division. The 2nd Regiment of the Reorganized 8th Cavalry Brigade and other units of the nationalist Reorganized 82nd Division including the field hospital, the engineering battalion, the communication battalion, the transportation company, the garrison group and others were deployed to Western Peak and Xiaojing () regions.
After the nationalist Reorganized 82nd Division had pushed toward eastern Gansu, the nationalists had successfully driven the local communist guerillas into the mountains of Meridian Ridge (Zi Wu Ling, ) in four weeks by taking advantage of their cavalry and the adaptation of their own guerrilla tactic against communist guerillas. Although the nationalists were expecting the enemy would attack in great numbers eventually, they had not anticipated the assault by the enemy main force would come so soon, and thus initially believed it was just the enemy guerillas grouped together for a counterattack, instead of the main force of the regular communist army. The defenders of Heshui, nonetheless, was well armed to take care themselves: the Heavy Weaponry Battalion of the Reorganized 8th Cavalry Brigade of the nationalist Reorganized 82nd Division at Heshui included an infantry support gun company, an anti-tank gun company, a heavy machine gun company and a communication platoon, and the battalion is one of the best unit among Ma clique's forces that were experts in urban defense. The Heavy Weaponry Battalion of the Reorganized 8th Cavalry Brigade of the nationalist Reorganized 82nd Division was further assisted by the Gansu 2nd Security Regiment whose troops were all locals who were very familiar with local terrain. The nationalist Reorganized 82nd Division Ma Jiyuan () had so much confident in this urban defense garrison of 1,300 men that he deployed them in the exposed town of Heshui, and history would later prove that he was right and his men would not disappoint him.
Order of battle Defenders: nationalist order of battle Reorganized 8th Cavalry Brigade of the nationalist Reorganized 82nd Division Garrison Group (Regiment) of the nationalist Reorganized 82nd Division Gansu 2nd Security Regiment Attackers: communist order of battle 359th Brigade of the communist 2nd Column Independent 4th Brigade of the communist 2nd Column Instructional Brigade of the communist 2nd Column
Second stage The detachments of communist 2nd Column under the command of Wang Zhen crossed Meridian Ridge and approached the town of Heshui. The 359th Brigade of the communist 2nd Column was assigned to take the town while the Instructional Brigade and the Independent 4th Brigade of the communist 2nd Column were tasked to ambush the reinforcement. As the 1st Regiment of the Instructional Brigade reached the Wormwood Grass Shop (Hao Cao Pu, ) area of Luo Er Plateau (Luo Er Yuan, ) region 10 km from Heshui, the communist scouts ahead were ambushed by the local nationalist cavalry on patrol. In a brief but fierce battle, a communist scout was captured alive by the nationalist cavalry. The communists feared that their plan was to be compromised, and attempted to rescue the captured scout, but Luo Er Plateau was a place extremely difficult to take but very easy to defend due to its terrain, and the 1st Regiment of the Instructional Brigade of the communist 2nd Column was forced to abort their futile attempts and move to the planned destination. The attackers therefore lost the element of surprise. At 4:00 AM on May 28, 1947, the 717th Regiment of the 359th Brigade made contact with nationalist garrison of Heshui to the northwest of the town, and all nationalists outside the town soon retreated behind the city wall. The commander of the Heavy Weaponry Battalion of the Reorganized 8th Cavalry Brigade of the nationalist Reorganized 82nd Division, Ma Shengzhi (), radioed the headquarters of the nationalist Reorganized 82nd Division at the town of Western Peak, claiming that the battle had already been raged on. By the evening of May 28, 1947, Ma Shengzhi radioed for help again, claiming that large enemy force was approaching the town of Heshui.
The enemy attackers were headed by Guo Peng (), the commander of the 359th Brigade of the communist 2nd Column. The 12th Regiment of the Independent 4th Brigade of the communist 2nd Column was also sent to join the assault on the town. The 717th Regiment of the 359th Brigade of the communist 2nd Column attack the town from northwest, while the 718th Regiment of the 359th Brigade and the 12th Regiment of the Independent 4th Brigade of the communist 2nd Column attacked the town from the east, and the 719th Regiment of the 359th Brigade of the communist 2nd Column was kept as reserve. However, the attacking communists were prevented from approaching the city wall, and it was not until the morning when the attacking enemy discovered why: the city wall extended toward a plateau to the northwest of the town, and defenders atop of the city wall on this plateau had perfect firing positions that could effectively block any attackers' advance toward the town. The defenders had deployed not only mortar and anti-tank guns, but several heavy machine guns as well. After futile attacks that lasted for an entire day and night, the attackers finally realized that this extension must be taken but with the current strength they had, they were simply unable to achieve this impossible task, and Guo Peng, the commander of the 359th Brigade of the communist 2nd Column, who was in the southwestern suburb of the town directing the battle, and he had no choice but to deploy the reserve, the 719th Regiment of the 359th Brigade of the communist 2nd Column ahead of schedule to attack the extension. By the noon of May 29, 1947, the 718th Regiment of the 359th Brigade and the 12th Regiment of the Independent 4th Brigade of the communist 2nd Column were able to take nationalist strongholds in the east and south just outside the city wall, and Eastern Pass (Dong Guan, ) of the town fell into the 718th Regiment of the 359th Brigade of the communist 2nd Column by the afternoon. After preparation, the 719th Regiment of the 359th Brigade of the communist 2nd Column launched its assault on the northwestern extension of the nationalist defense, but the defenders would not let them succeed: while the enemy was busy attacking, the defenders sent out a large force via tunnels to counterattack the attacking enemy from behind, and inflicted heavy casualties on the communist attackers, which was forced to halt their attack.