Peter C. Baker writes in The Nation on September 10, 2013:
Modern warfare changed on a Harvard soccer field in the summer of 1942. On July 4 of that year, Louis Fieser, head of the National Defense Research Committee’s “Anonymous Research Project No. 4,” flipped a switch, triggering a white phosphorous explosion inside a bomb filled mostly with jellied gasoline. The use of flame in war had been on the decline since the spread of gunpowder in the thirteenth century, but Fieser showed that with napalm, planes could drop sticky fire from the sky.