“Carpet bombing” is a catchphrase concocted by civilian journalists who didn’t know the first thing about bomber aircraft: no such words, not in the official doctrine of either Britain’s RAF Bomber Command doctrine nor USAAF strategic bombardment doctrine.
Both British and US air theorists and leaders intended to use air strikes against future adversaries’ home territory using extreme precision, but actually sustaining such air efforts in the face of Third Reich air defenses proved too costly, in terms of attrition. It drove RAF Bomber Command to undertake night strikes, which proved to be less accurate. To compensate, they developed specially trained and experienced “Pathfinder” crews that preceded the main force and dropped color-coded marker flares on the targets (or as close as they could get to targets). Then the main force came over in huge numbers, saturating defenses and dumping munitions on the colored marker flares (when they could see them). Additionally, there was the policy of deliberate “de-housing” - attacking the residences of German industrial labor force, to kill them or drive them from the vicinity of the factories. This became problematic over time as Nazi propaganda made hay of it, and British public opinion wavered as German civilian morale did not implode completely, as did that in Britain during World War One: riots occurred after Imperial German air strikes on London.
American theory centered around the “industrial bottleneck” - the idea that there existed a handful of key industrial products common to all weapons production: if their production could be taken out or simply degraded by high-precision strikes, output of war materiel would slow or stop. Ball bearings were the first to be attacked; the German effort did not falter much, and after severe attrition due in part to bungled timing and bad luck, USAAF dropped that approach.
Precision bombing depended not only on precise delivery of bombs by the aircrews, but equally heavily on precision surveillance and intelligence - first to find and identify the targets, then assess damage after strikes, and finally to determine change in output.
Not until well after World War Two ended did the Western Allies discover that they’d left off striking too early, in several cases only a strike or two short of terminating an industry completely. In the case of the ball-bearing attacks, production was reduced to a trickle, and German workers were in some instances forced to carry the day’s output of ball bearings to their customers assembling tank transmissions or aircraft - in knapsacks on bicycles. This wasn’t publicized until the 1980s.
In the end, the general conclusion about targeting air strikes against the Nazi war machine was to hit oil production and the transportation network.
The problems of hitting the warmaking capability of the Home Islands of Imperial Japan were somewhat different.
It was found that precision strikes from B-29s flying above 30,000 feet were tough to prosecute, because of the previously unknown jet stream, which was impossible to predict given the level of meteorological knowledge of those days. It was found that a bomber that flew into the jet stream quickly overran rate limits of its bombing computers.
Post-strike analysis discovered that Japanese industrial facilities had succeeded in dispersing machinery and production activities to a degree hitherto unknown. Simply striking what was known to be a factory building thus accomplished very little: Curtis E Lemay was quoted about his examination of a post-war photo that showed a row of drill presses, standing all alone in the ruins of what had been a workers’ housing neighborhood, burned to ash otherwise.
Hence the decision to abandon high altitude daylight precision strikes in favor of strikes with incendiaries, against large urban areas. In an echo of what the RAF did earlier, the B-29s went in at night at relatively low altitudes, with most defensive armament and ammunition removed, to save weight in favor of more incendiaries.
Over 60 cities were thus hit, not merely Tokyo. Several senior USAAF leaders remarked after the war that they foresaw a Japanese surrender before the scheduled invasion (1 November 1945) and without the use of the atomic bombs.
Another aspect of the air attack against Imperial Japan was the interdiction of coastal maritime traffic. Japan was dependent on merchant-ship deliveries from northern China and its conquered territories southwest and south, but was also dependent on inshore shipping to move a lot of stuff around the Home Islands. Submarines of the US Navy had already done much to halt the over-ocean traffic, but they could not operate well in shallow coastal waters. A portion of the B-29 force was devoted to dropping mines in ports and along shore-hugging sea-lanes; though this effort lasted only a couple months near the end of the war, it accounted for 8 to 11 percent (if memory serves) of total merchant-vessel tonnage lost by Japan.
Forum members are invited to research the topic further, in the US Strategic Bombing Survey. Also, Richard B Frank’s book “Downfall” summarizes the strategic situation and decision rationales neatly.
We did. It just took awhile to get close enough to do it.