Flamethrowers
The Germans were the first to use the "modern flamethrower." But, the Chinese and Byzantines used weapons that hurled flames during the Medieval period. Flamethrowers, or Flammenwerfer in German, are devices that spray out burning gas. The purpose was to set up for use in three specialist squadrons. These improved the lives of the people who were using them because it helped them greatly at close combat, and when they were in trenches and enemy soldiers were trying to get to the trenches, they would be able to kill the soldiers, without ruining their own trenches. But it did not improve the lives of the enemies for obvious reasons. Some negative impacts of this were that it made it very easy for Germans, and later others who made and used flamethrowers, to use in close proximity, so there were many deaths because of these. Also, they could explode, so people died that way too.