Flame Thrower, a device used chiefly in close combat in war. It is particularly effective against enclosed defensive positions, such as pillboxes, blockhouses, and caves. The flame thrower was first used by the Germans in World War I. It became an important weapon of United States troops in routing the Japanese from numerous Pacific islands in World War II.

The portable flame thrower consists of a metal tube about three feet (90 cm) long connected to one or more tanks of fuel and a tank of compressed air. The fuel, usually napalm (jellied gasoline), is ignited by a pilot light as it is forced from the nozzle of the tube by air pressure. The resulting tongue of flame is more than 50 yards (45 m) long and has a temperature in excess of 2,200 F. (1,200 C.). A larger type, on tanks and other mechanized units, throws a flame more than 150 yards (135 m).

Flame throwers also have many peacetime uses. They are employed by railways to burn weeds along the right-of-way during the summer, and to keep switches and guard rails free of ice and snow during winter. They also are used by farmers and fruitgrowers to burn weeds and caterpillar nests in trees. Other winter uses include the melting of snow and ice from sidewalks and driveways, and the thawing of waterpipes.