After the Battle of Wuhan, Wuhan was the base of the 11th Army of the Imperial Japanese Army, and was surrounded by the 5th and 9th Military Regions of the National Revolutionary Army. Nanchang was a railway center, the major supply line between the 3rd and 9th Military Regions , and site of the airbase threatening Japanese shipping in Yangtze River. In addition, its proximity to the center of the Shanghai- Wuhan strip controlled by Japan was a strategic threat.
The 9th Military Region was reshuffled, with Chen Cheng staying as the supreme commander in name and Xue Yue becoming the commander in actuality. 200,000 troops in 52 divisions were gathered near Nanchang. However, lacking vehicles, the reorganization took a long time and the planned attack was delayed.
Order of Battle, Battle of Nanchang
Japanese troops had tried to approach Nanchang during the Battle of Wuhan, but they were stopped at Xiushui River. Where they had to wait for reinforcements, and started the second invasion with 120,000 troops. Following an artillery barrage Japanese troops began crossing the Xiushui River . Starting at 7:00am on March 21st they advanced 2 km , and began to build bridges. On March 23, Wucheng where the Xiushui River enters Poyang Hu was devastated by sustained naval bombardment and airstrikes followed by a landing by Naval Landing forces. By March 26, Japanese troops supported by tanks had broken out of their Xiushui River bridgehead and reached the west gate of Nanchang, defeating Chinese reinforcements from the 3rd Military Region. By March 27, Nanchang had fallen after being surrounded and put under siege by Japanese forces. This was the end of the first phase of the battle.
Chinese counterattack & retreat
However, the battle was not over. During a period lasting until the end of April some Japanese forces were moved to support operations in other areas . This weakening of available Japanese manpower had consequences. On April 21, a surprise attack by the forces of the 3rd and 9th Military Regions allowed for a breakthrough by the 32nd Army Group that allowed a Chinese spearhead to reach the outer area of Nanchang in 5 days. However, under heavy attack from Japanese Aviation and facing a Japanese garrison re-enforced by components of the Navy they were unable to lay an effective siege and retreated on May 9.
Subsequent to this battle, the major supply line of the 3rd Military Region of the National Revolutionary Army and the southeast provinces of China came under increasing threat.