US M2/M2A1 Flamethrower
After a dismal first attempt at designing a flamethrower (the M1) in 1941, the US Chemical Corps along with several universities and industrial partners put in a lot of research to develop a more usable and effective flamethrower. The result was the M2, which went into production in early 1944. It would prove to be an exceptionally effective weapon in the island-hopping campaign towards the end of the war.
The M2 was arguably the best flamethrower fielded by any military during the war, with a number of excellent design features. These included: