The Second Sino-Japanese War was a conflict that began in 1937 and lasted until 1945, primarily between the Republic of China and the Empire of Japan. It was marked by significant battles, including the Battle of Shanghai and the Nanjing Massacre, where Japanese forces committed widespread atrocities against Chinese civilians. The war was part of a larger struggle during World War II. The conflict resulted in millions of casualties and widespread destruction in China. It ended with Japan's defeat in 1945, leading to the establishment of the People's Republic of China in 1949. The war significantly impacted China's national identity and its relations with Japan.