Street fighting in Berlin between Government troops and Spartacists, during the Spartacist uprising which followed Germany's defeat in World War I. (Photo by Keystone/Getty Images). 1919

Soldiers of the 70th division of the American 7th Army hold up a Nazi flag and a portrait of Adolf Hitler, taken during the World War II capture of Saarbrucken. (Photo by Horace Abrahams/Keystone/Getty Images). 22nd March 1945

A .44 Colt Dragon with a traditional Cowboy's hat. This weapon was originally used in the Mexican War of 1846-8 and it is typical of the type used in the “Wild West” of America. (Photo by Orlando /Three Lions/Getty Images). Circa 1950

In this Friday, August 9, 2019, file photo, Pakistan Rangers soldiers face Indian Border Security Force soldiers at a daily closing ceremony on the Indian side of the Attari-Wagah border. India's recent clampdown has a long history in Kashmir and the conflict has existed since the late 1940s, when India and Pakistan won independence from the British empire and began fighting over rival claims to the Muslim-majority territory. India and Pakistan have fought two of their three subsequent wars over Kashmir, and each administers a portion of the region. India has long seen the Kashmiri struggle for self-determination as Islamabad's proxy war against New Delhi. (Photo by Prabhjot Gill/AP Photo/File)

In this September 10, 1977, file photo, from left, Hua Guofeng, Chinese Communist Party (CCP) chairman and Mao Zedong's immediate successor; Ye Jianying, CCP vice chairman and future ceremonial head of state; Deng Xiaoping, no formal titles at the time but soon to emerge as paramount leader during the reform era; Li Xiannian, CCP vice chairman and future president; Wang Dongxing, head of the leadership bodyguard unit who helped topple the Gang of Four, view the body of later Chinese leader Mao Zedong in Beijing. (Photo via AP Photo)

The lightest material ever made has been produced by a team of scientists in China, a Chinese university announced.