During the Battle of Dadonggou in the Yellow Sea during the Sino-Japanese War of 1894 - 1894, although my country lost five warships, six of the enemy's 12 warships were severely injured. Among them, two of the three ships that were towed back to Japan sank. The fourth flagship, Matsushima, could not be repaired and had to withdraw from the warship sequence. It can be seen that the Japanese army's losses were not light. However, Li Hongzhang deliberately exaggerated the losses in the Yellow Sea Battle, proposed the policy of "protecting ships and avoiding battle," and ordered all the fleet to hide in Weihaiwei in an attempt to preserve strength and drag out the war until the end.

Weihaiwei is located at the eastern end of the north bank of the Shandong Peninsula. It is a dangerous coastal defense fortress. The port is in a semicircle shape, and Liugong Island and Ridao line the mouth of Weihai Bay, forming a natural barrier at the sea. There are 17 batteries and more than 160 cannons on the coast and on the island. According to the situation at that time, as long as we persisted in resistance and took the initiative to attack, we could completely compete with the Japanese army. However, Li Hongzhang's order to "protect ships" put the Beiyang Fleet in a completely passive position.

On January 19, 1895, the Japanese invaders, who did not dare to attack Weihaiwei head-on, still used the same tactics as attacking Lushun. They sent the invading army to land on Chengshan Mountain on the Shandong Peninsula, in an attempt to outflank the rear and invade Weihaiwei from behind to eliminate the Beiyang Navy trapped in the port. At that time, there were 20,000 Japanese troops, and only 400 Qing troops stationed in Chengshan Mountain. The Beiyang Navy, which was bound by Li Hongzhang's order to "protect the ship", could only shrink into Weihaiwei and wait honestly for the Japanese army to advance step by step from behind.