This invention by 15-year-old Chester Greenwood was used by soldiers during World War I.
Bolt-action rifle
Earmuffs
Gas mask
Grenade
Earmuffs. In 1873 in Farmington, Maine, Greenwood invented what he called ear protectors to keep his ears warm when he iceskated outside. The earmuffs produced by Greenwood’s Ear Protector Factory were in great demand by World War I soldiers.