The first air-to-air combat attempts were made by throwing bricks and grenades from plane to plane during WWI.
In WWI Canadian soldiers used urine-soaked cloths as primitive respirators against chemical attacks. The ammonia in urine would react with the chlorine, neutralizing it, and that the water would dissolve the chlorine, allowing the soldiers to breathe through the gas.
During WWI, Dominic “Fats” McCarthy was awarded the Victoria Cross after he, virtually unaided, killed 22 Germans, captured 5 machine guns, 50 prisoners, and half a kilometer of the German front. When it was over even the prisoners he’d captured patted him on the back for what he’d done.
The youngest soldier in WWI was only 8 years old.
In 1999 a fisherman found a love letter in a bottle from a soldier in WWI. He returned said letter to the now deceased widows 86 year old daughter.
During WWI, a British soldier showed mercy to a wounded German infantryman… who later turned out to be Adolf Hitler.
Germany made its final reparations payment from the WWI Treaty of Versailles in 2010.