Defense of the Great Wall

The defense of the Great Wall (traditional Chinese: 長城抗戰; simplified Chinese: 长城抗战; pinyin: Chángchéng Kàngzhàn) (January 1 – May 31, 1933) was a campaign between the armies of the Republic of China and the Empire of Japan, which took place before the Second Sino-Japanese War officially commenced in 1937 and after the Japanese invasion of Manchuria in 1931. It is known in Japanese as Operation Nekka (熱河作戰, Nekka Sakusen) and in many English sources as the First Battle of Hopei.

Source: Wikipedia — Defense of the Great Wall (CC BY-SA 4.0)