The Communists had already targeted Dachen Archipelago when they attacked Yijiangshan Islands, but the Communists were incapable of simultaneously taking both. When the Communists bombed Dachen Archipelago during the Battle of Yijiangshan Islands, it was mainly to prevent the Nationalist garrison of Dachen Archipelago from reinforcing Yijiangshan Islands. In fact, from 1 November 1954 to 4 November 1954, the Communist air force flew 49 sorties to bomb Dachen Archipelago, but none of the 721 bombs dropped hit their intended targets. On 10 November 1954, the Communist bombers flew 28 sorties and Communist fighters flew 46 sorties in support of the bombers to strike Nationalist warships in the Dachen Archipelago, but only resulted in minor damages of a mere five warships.
The battle
Air raids
After the main battle of the Battle of Yijiangshan Islands had subsided, the Communists immediately turned their attentions to Dachen Archipelago before declaring the Yijiangshan Islands secured. On 19 January 1955, the first Communist bombing mission specifically targeting Dachen was carried out by combat-hardened aircrew with experience. Due to the previous two unsuccessful Communist bombing missions, the Nationalists believed that this third air raid would be equally inept and were not fully prepared. As a result, the infrastructures on the islands, especially those for communication, were severely damaged. The casualties were minimal, but the local Nationalist garrison was forced to use unencrypted radios to communicate with Taiwan and among themselves. Since the Communists used Nationalist equipment captured during the Chinese Civil War, they were able to intercept Nationalist communications. The second wave of attack also occurred on the same day on 19 January 1955. Though the local Nationalist garrison regrouped and set up more effective air defence, the effort was futile because the second wave of attack struck a target completely unexpected by the defenders: the reservoir, which was not considered a military target of any significance. The reservoir was completely destroyed and, without any fresh water supply readily available, it was nearly impossible to defend the archipelago. On 2 February 1955, the Communist air force bombed the Southern Deer Mountain Archipelago.
The Dachen Retreat
After much debate, the Nationalist government in the Republic of China controlling the Dachen and adjacent archipelagos finally agreed with the Americans to hold out until an evacuation could be carried out by the American Navy in February 1955 to Taiwan more than 200 miles to the south. The decision was made to withdraw on 5 February 1955, and the U.S. Seventh Fleet used 132 boats and 400 aircraft to move 14,500 civilians, 10,000 Republic of China servicemen, and 4,000 guerrilla fighters, along with 40,000 tons of military equipment and supplies from the island. After the evacuation, the last Flag of the Republic of China in Dachen was lowered by Chiang Ching-kuo, and the Zhejiang province government was abolished in the Republic of China as Dachen was their last stronghold in the province.
Last phases
After the retreat, Northern Muntjac Island was the first to be taken by the People's Liberation Army on 8 February 1955, and by 12 February 1955, the entire Dachen Archipelago had fallen into the enemy hands. On 13 February 1955, the entire Southern Muntjac Archipelago was taken by the Communists. The Nationalists had left a single regiment to garrison the Southern Deer Mountain Archipelago to the south of Dachen Archipelago for a symbolic struggle, and the regiment held out until late February 1955. The local commander realized the struggle was futile and was unwilling to waste troops in the lost cause, and thus asked and received permission to withdraw. On 26 February 1955, the People's Liberation Army took the Southern Deer Mountain Archipelago and the battle concluded.
Outcome
For the Communists, the gaining of these archipelagos eliminated the Nationalist threat to the vital coastal shipping line, and the Nationalist bases to strike coastal regions, but as Chiang Kai-shek grudgingly allowed the archipelagos to fall to the Communists so that the other offshore island groups, Kinmen and Matsu, could be successfully defended, the result of the battle could therefore be considered a draw.
