Flamethrowers
These days, no one really has to be told what a flamethrower is; they have already appeared in so many different types of media that you are likely already familiar with their fundamental functionality. A soldier has a tank of fuel strapped to his back, and a spraying mechanism is attached to it that will pump the fuel out of the tank and ignite it, resulting in a never-ending shower of terrible Hellfire.
A flamethrower poses a terrible risk to the person using it in addition to being an extremely effective weapon and technique of terrifying your adversaries. A soldier essentially points a light at themself that any opponent can see and target the instant they step foot on the battlefield and light up a flamethrower. Aside from putting you at risk for enemy fire, the fuel tank itself was also at risk of being struck by errant fire and exploding.
According to some reports, a flamethrower operator's combat life lasted on average 5 minutes. This was partly because they made themselves out to be easy targets, and partly because a flamethrower's fuel tank would be totally depleted in a matter of seconds, leaving the user mostly defenseless.
Country of origin: Germany