People have brought up counterclaims in response to my assertion that "by the time of your source the war in Europe and Asia had been raging for years already and civilian bombing carried out countless times. While the Allies sure did some nasty things, they were far less than that of the Axis - saying otherwise is historical revisionism"
http://blog.nuclearsecrecy.com/2013/08/30/who-made-that-firebomb/ "is the AN-M69 Incendiary Bomb. This was a cluster-based napalm weapon developed by the Standard Oil Company, specifically designed to destroy Japanese civilian houses. Standard Oil’s development of the AN-M69 started in early October 1941 — almost exactly two months before the attack on Pearl Harbor."
and
The work was funded by the Office of Scientific Research and Development. What makes it disturbing is that the engineering is very explicitly directed towards the destruction of civilian life.
The effects testing, done very carefully by both universities (Harvard again, along with the University of Chicago), corporations (Standard Oil, Texas Company), and the military (Ordnance Department) are also pretty grim. Some 80 million pounds of napalm were produced and used during the war.
USA did the pioneering and perfecting of mass burning of millions of civilians Each B-29 could carry 40 clusters in their bomb bays. So that’s 1,520 AN-M69s per plane, and the raids could range from dozens to hundreds of planes. You can do the math, there. Over 40,000 tons of AN-M69s were dropped on Japanese cities during the war. It took about 125 tons per square mile to completely burn out an area of a Japanese city. The AN-M69 had, a once-classified postwar report announced triumphantly, “the highest fire-starting efficiency per cluster, or per ton, or per bomber of any incendiary bomb” developed during the war. Some 80 million pounds of napalm were produced and used during the war.
I note that a somewhat similar thread has been posted, but it doesn't have clear examples and explanations of Axis behavior (both Germany and Japan) pioneering civilian bombing.
This is all going to depend on definitions and scale.
The Germans in WW1 dropped bombs using the Zeppelin. The British dropped bombs in Iraq and in Somaliland in 1920 using airplanes to quell rebellions. The first full scale use of aerial bombardment, however, took place during the Spanish Civil War (1936-1939). The bombing was done by Francisco Franco's Nationalist forces in Spain with helped from the air force of Nazi Germany. Picasso's Guernica made this infamous.
"is the AN-M69 Incendiary Bomb. This was a cluster-based napalm weapon developed by the Standard Oil Company, specifically designed to destroy Japanese civilian houses. Standard Oil’s development of the AN-M69 started in early October 1941 — almost exactly two months before the attack on Pearl Harbor."
The Standard Oil Company was most certainly not involved in the development of firebombs in 1941, considering it was dissolved by the Supreme Court in 1911.
If we go by the standard definition of "pioneer" as being the "first to do something," and if we go by your apparent WWII context, then I think the answer would be the Axis. As others have mentioned in this thread, and the one that you linked, Axis bombing explicitly targeting civilian population centers predated that of the Allies, with the Bombing of Warsaw (1939) and Rotterdam (1940) from the Germans, and the Bombing of Chongqing (1938) from the Japanese.
If you are using "pioneering" in more of a "who developed and perfected this first?" sort of sense, then I think the answer is a bit more muddled. First, though, I wanted to mention a major issue that I had with the source you provided. The author seems to suggest that the US "invented" the firebomb.
So who made that firebomb? A now all-too-familiar mixture of American industry, universities, and government.
I am sorry, but this is patently untrue. As others have mentioned below, the Germans made use of firebombs all the way back in the Spanish Civil War in the late '30s. In addition, the Germans used their B1 E1 ZB incendiary bombs on a number of civilian targets in the UK, like in their Coventry Blitz of late 1940.
If we want to talk about "disturbing engineering...directed towards the destruction of civilian life," why don't we look at the B1 which used a magnesium and thermite compound to start fires so hot that they could not be extinguished by water? Or the fact that these B1s contained additional small explosives that were designed to detonate after landing, so as to discourage firefighters? Or what about the groundbreaking German V2 rocket artillery, designed to attack London from afar?
Now, this in no way "justifies" what the allies did during the war. Certainly the American firebombing of Japan may have been some of the most brutally terrifying bombing campaigns of the entire war. Much of this may have been helped by their extensively developed AN-M69 bombs. However, it seems clear that incendiary and civilian bombing tactics were developed and researched by both sides of the war; the M69 was certainly not the first "cluster-based incendiary device" targeting civilian structures. It would be very disingenuous to suggest, as the author of your source does, that America "pioneered" or was alone in its quest for maximizing its air raid capabilities.
Source:
You can check out this page for a brief overview of incendiary bombs.
As the author of that page:
The US pioneered the technique, but...
They certainly perfected it to its gristly end, took it to its most extreme conclusions (area bombing).
Which is a claim, by the way, that the US Army Air Forces themselves would have agreed with at the time. It's not revisionist — it's understanding it as how they would have understood it.