July 7, 1937: Second Sino-Japanese War begins

On this day in 1937, the Second Sino-Japanese War began. It would later merge with the Second World War, where it was responsible for 90% of the casualties in the Pacific Theatre.

Some historians date the conflict to 1931, when the Japanese captured Manchuria, a large area of China north of the Korean Peninsula.

The resulting truce lasted until 1937, when an apparent skirmish at the Lugou Bridge, about 10 miles southwest of Beijing, escalated to a full-scale Japanese attack. (The 12th-century structure was so praised for its beauty by a certain European visitor that it is often referred to as the Marco Polo Bridge.)

The capital fell the following month. The Japanese were satisfied with their gains, but Chinese leader Chiang Kai-Shek called for all-out resistance.

The Japanese responded in December with what is today known as the Rape of Nanjing, when up to 300,000 civilians died.

The History Channel has more.

Image: Japanese entering Beiping, China. Associated Press via Wikimedia Commons