A Republican farmer defending a farm on the outskirts of Irun against Nationalist forces during the Spanish Civil War, 6th September 1936. A comrade lies dead by his side. (Photo by Keystone/Hulton Archive/Getty Images)

South Korean university students prepare for an establishment ceremony of the Reserve Officer Training Corps (ROTC) for female cadets at Sookmyung Women's University on December 10, 2010 in Seoul, South Korea. The South Korean defense ministry has agreed to admit women into it's college-based Reserve Officers' Training Program for the first time since the program began in 1963. (Photo by Chung Sung-Jun/Getty Images)

Visitors crowd an artificial wave swimming pool at a tourist resort to escape the summer heat in Daying county of Suining, Sichuan province, China, July 11, 2015. (Photo by Reuters/Stringer)

A soldier of the Household Cavalry Mounted Regiment falls off a horse during a practice to participate in the state ceremonial surrounding this year's Platinum Jubilee celebrations at Hyde Park in London, Thursday, March 31, 2022. Around 170 horses and personnel of the Household Cavalry Mounted Regiment left their Hyde Park Barracks to form up and be inspected by the General Officer Commanding the Household Division, Major General Christopher Ghika. (Photo by Frank Augstein/AP Photo)

Fighters of Wagner private mercenary group pull out of the headquarters of the Southern Military District to return to base, in the city of Rostov-on-Don, Russia on June 24, 2023. (Photo by Alexander Ermochenko/Reuters)

Soldiers of Ukraine's National Guard 1st brigade Bureviy (Hurricane) fire a recoilless cannon during combat training at a military training ground in the north of Ukraine Friday, November 3, 2023. (Photo by Efrem Lukatsky/AP Photo)

Ukrainians attend an open military training for civilians on a training range in Kiev, Ukraine, 06 February 2022. According to a survey conducted by the Kiev International Institute of Sociology (KIIS) from December 2021, 50.2 percent of Ukrainians said they would resist in case of a Russian military intervention into their city, town or village. Every third respondent to the poll said they were ready to engage in armed resistance, and 21.7 percent said they were ready to participate in civil resistance actions. (Photo by Sergey Dolzhenko/EPA/EFE/Rex Features/Shutterstock)

A German rifleman beside the corpse of a French soldier in a trench at Fort Vaux, France, 1916. (Photo by Hulton Archive/Getty Images)