The M1's unreliability and lack of developed tactics resulted in the failure of the first flamethrower attack on a Japanese fortification in December 1942.

The nozzle of the weapon was located at the end of a long, thin pipe, which was connected to the backpack via a hose.

Used first in a battle on July 30, 1915 at Hooge in Flanders, the Germans surprised the British and French forces in an assault that inflicted almost 800 casualties.

[1] The arrival of the American troops in December 1917 provided the United States with first hand experience in the fielding of flamethrower systems.

The Americans experimented with and developed flamethrower systems during the war, but were curtailed by the signing of the armistice in November 1918.

The previously aforementioned tactics against their deployment and the extreme danger of the flamethrower system contributed to the American forces regarding it as a total failure.

General Amos A. Fries, chief of the Chemical Warfare Service department from 1920 to 1929, of the American Expeditionary Forces commented that flamethrowers were "one of the greatest failures among the many promising devices tried out on a large scale in the war."

The Chemical Warfare Service worked to redesign flaws in the E1's design, including an ability to fire from a prone position, dropping gas pressure levels, and weight to produce the E1R1, contracted through the Kincaid Company, in March 1941.

The E1 was redesigned by the Chemical Warfare Service and labeled Experiment 1 Revision 1 and was ready for testing in March 1941.

The compressed nitrogen was separated away from the fuel reservoir, a feature carried forward in all subsequent models.

Issues - Weight, easily damaged parts, and access to the control valves were identified during testing as being problematic.

Gasoline and oil mixtures sprayed as it left the barrel of the flame gun, whereas napalm thickened fuel left the barrel in a compact stream capable of ricocheting off of and into openings and subsequently sticking to flat surfaces.

Initial tests showed that the current M1 platform was incapable of providing the ideal range with napalm.