One telling photo in the museum's collection was taken in 1944, when 12 members of the same family posed for the snapshot, standing next to a giant date tree in front of their home in Shandong province. They were all Communist soldiers who had fought in and outside their native province in East China.
Overseas Chinese also joined the war effort. While many donated money, others returned to China to serve as fighter pilots, drivers or mechanical engineers. About 4,000, most from Southeast Asian countries, worked along the "Burma Road", a crucial supply line linking Kunming in Yunnan province with Lashio in Burma, now Myanmar. They helped to transport about 300 metric tons of wartime materials every day.
Only 1,800 survived; the rest died in bombing raids, of disease, or were reported missing in action.
Although 2 billion people across the globe fought in WWII, the number of Chinese combatants was 450 million, 22.5 percent of the total. In all, 35 million Chinese, including civilians, died, compared with 27 million Soviet citizens, 1.2 million Britons and 1 million United States nationals.
On Sept 9, 1945, Japan formally surrendered to China at a ceremony in Nanjing, capital of Jiangsu province, 25 days after Emperor Hirohito announced his country's surrender to the Allies on Aug 15.
"On Aug 16, the firework celebrations by people of the Republic of China went on from night until the next morning. All we could do was lower our heads, and go from being Japanese soldiers to simply being Japanese," wrote Kensuke Konishi on a homemade Japanese flag he had kept since leaving his homeland in January 1945, and on which he diligently recorded the major events during his period of service. The flag is now owned by the memorial museum in Beijing.
The journey took the new recruit first to Korea and then Northeast China, both Japanese colonies at the time. From there, the Japanese army marched south, arriving in Nanjing in mid-February.
In recent years, Xu Yong, a senior researcher at Peking University in Beijing, has regularly visited Japan, where he has researched archival materials that shed light on what he believes was the "inevitability" of the July 7 Incident.