Strategic bombing during World War II
involved sustained strategic bombing of railways, harbours, cities, workers' and civilian housing, and industrial districts in enemy territory. Strategic bombing as a military strategy is distinct both from close air support of ground forces and from tactical air power. During World War II, many military strategists of air power believed that air forces could win major victories by attacking industrial and political infrastructure, rather than purely military targets. Strategic bombing often involved bombing areas inhabited by civilians, and some campaigns were deliberately designed to target civilian populations in order to terrorize them or to weaken their morale. International law at the outset of World War II did not specifically forbid the aerial bombardment of cities – despite the prior occurrence of such bombing during World War I, the Spanish Civil War, and the Second Sino-Japanese War.
Strategic bombing during World War II in Europe began on 1 September 1939 when Germany invaded Poland and the Luftwaffe began bombing Polish cities and the civilian population in an aerial bombardment campaign. As the war continued to expand, bombing by both the Axis and the Allies increased significantly. The Royal Air Force, in retaliation for Luftwaffe attacks on the UK which started on 16 October 1939, began bombing military targets in Germany, commencing with the Luftwaffe seaplane air base at Hörnum on the 19–20 March 1940. In September 1940 the Luftwaffe began targeting British civilians in the Blitz. After the beginning of Operation Barbarossa in June 1941, the Luftwaffe attacked Soviet cities and infrastructure. From February 1942 onward, the British bombing campaign against Germany became even less restricted and increasingly targeted industrial sites and civilian areas. When the United States began flying bombing missions against Germany, it reinforced British efforts. The Allies attacked oil installations, and controversial firebombings took place against Hamburg, Dresden, and other German cities.
In the Pacific War, the Japanese frequently bombed civilian populations as early as 1937–1938, such as in Shanghai and Chongqing. US air raids on Japan escalated from October 1944, culminating in widespread firebombing, and later in August 1945 with the atomic bombings of Hiroshima and Nagasaki. The effectiveness of the strategic bombing campaigns is controversial. Although they did not produce decisive military victories in themselves, some argue that strategic bombing of non-military targets significantly reduced enemy industrial capacity and production, and was vindicated by the surrender of Japan. Estimates of the death toll from strategic bombing range from hundreds of thousands to over a million. Millions of civilians were made homeless, and many major cities were destroyed, especially in Europe and Asia.
Legal considerations
The Hague Conventions of 1899 and 1907, which address the codes of wartime conduct on land and at sea, were adopted before the rise of air power. Despite repeated diplomatic attempts to update international humanitarian law to include aerial warfare, it was not updated before the outbreak of World War II. The absence of specific international humanitarian law did not mean aerial warfare was not covered under the laws of war, but rather that there was no general agreement of how to interpret those laws. This means that aerial bombardment of civilian areas in enemy territory by all major belligerents during World War II was not prohibited by positive or specific customary international humanitarian law.Many reasons exist for the absence of international law regarding aerial bombing in World War II. Most nations had refused to ratify such laws or agreements because of the vague or impractical wording in treaties such as the 1923 Hague Rules of Air Warfare. Also, the major powers' possession of newly developed advanced bombers was a great military advantage; they would be hard pressed to accept any negotiated limitations regarding this new weapon. In the absence of specific laws relating to aerial warfare, the belligerents' aerial forces at the start of World War II used the 1907 Hague Conventions — signed and ratified by most major powers — as the customary standard to govern their conduct in warfare, and these conventions were interpreted by both sides to allow the indiscriminate bombing of enemy cities throughout the war.
General Telford Taylor, Chief Counsel for War Crimes at the Nuremberg Trials, wrote that:
Article 25 of the 1899 and 1907 Hague Conventions on Land Warfare also did not provide a clear guideline on the extent to which civilians may be spared; the same can be held for naval forces. Consequently, cyclical arguments, such as those advanced by Italian general and air power theorist Giulio Douhet, do not appear to violate any of the convention's provisions. Due to these reasons, the Allies at the Nuremberg and Tokyo Trials never criminalized aerial bombardment of non-combatant targets and Axis leaders who ordered a similar type of practice were not prosecuted. Chris Jochnick and Roger Normand in their article The Legitimation of Violence 1: A Critical History of the Laws of War explains that: "By leaving out morale bombing and other attacks on civilians unchallenged, the Tribunal conferred legal legitimacy on such practices."
Ethical considerations
The concept of strategic bombing and its wide-scale implementation during WWII led to a post-war debate if it was moral.Three separate lines of ethical reasoning emerged.
The first was based on the Just War theory and emphasized that noncombatants possess an inherent right to be spared from the harm of war and should not be intentionally targeted. John C. Ford, SJ, made such an argument in an article in 1944. Noncombatant immunity and proportionality in use of force were insisted upon.
The second approach was grounded in the so-called "industrial web theory" that proposed to concentrate on destroying enemy military, industrial, and economic infrastructure instead of forces in the field as the fastest way to win the war. Proponents of this approach argued that civilian deaths inflicted by strategic bombing of the cities during the WWII were justified in the sense that they allowed a shortening of the war and thus helped to avoid many more casualties.
The third approach was demonstrated by Michael Walzer in his Just and Unjust Wars. Walzer formulated the so-called "supreme emergency" thesis. While agreeing in general with prior Just War theoretical postulates, he came to a conclusion that a grave threat to a moral order would justify the use of an indiscriminate force.
Air Marshal Sir Robert Saundby concluded his analysis of the ethics of bombing by these words,
Europe
Policy at the start of the war
Before World War II began, the rapid pace of aviation technology created a belief that groups of bombers would be capable of devastating cities. For example, British Prime Minister Stanley Baldwin warned in 1932, "The bomber will always get through."When the war began on 1 September 1939 with Germany's invasion of Poland, Franklin D. Roosevelt, President of the armed neutralitarian United States, issued an appeal to the major belligerents to confine their air raids to military targets, and "under no circumstances undertake bombardment from the air of civilian populations in unfortified cities". The British and French agreed to abide by the request, with the British reply undertaking to "confine bombardment to strictly military objectives upon the understanding that these same rules of warfare will be scrupulously observed by all their opponents". Germany also agreed to abide by Roosevelt's request and explained the bombing of Warsaw as within the agreement because it was supposedly a fortified city—Germany did not have a policy of targeting enemy civilians as part of their doctrine prior to World War II.
The British Government's policy was formulated on 31 August 1939: if Germany initiated unrestricted air action, the RAF "should attack objectives vital to Germany's war effort, and in particular her oil resources". If the Luftwaffe confined attacks to purely military targets, the RAF should "launch an attack on the German fleet at Wilhelmshaven" and "attack warships at sea when found within range". The government communicated to their French allies the intention "not to initiate air action which might involve the risk of civilian casualties".
While it was acknowledged bombing Germany would cause civilian casualties, the British government renounced deliberate bombing of civilian property, outside combat zones, as a military tactic. The British changed their policy on 15 May 1940, one day after the German bombing of Rotterdam, when the RAF was given permission to attack targets in the Ruhr Area, including oil plants and other civilian industrial targets which aided the German war effort, such as blast furnaces that at night were self-illuminating. The first RAF raid on the interior of Germany took place on the night of 15/16 May 1940 while the Battle of France was still continuing.
Early war in Europe
Poland
During the German invasion of Poland, the Luftwaffe engaged in massive air raids against Polish cities, bombing civilian infrastructure such as hospitals and targeting fleeing refugees. Notably, the Luftwaffe bombed the Polish capital of Warsaw, and the small towns Wieluń and Frampol. The bombing of Wieluń, one of the first military acts of World War II and the first major act of bombing, was carried out on a town that had little to no military value. Similarly, the bombing of Frampol has been described as an experiment to test the German tactics and weapons effectiveness. British historian Norman Davies writes in Europe at War 1939–1945: No Simple Victory: "Frampol was chosen partly because it was completely defenceless, and partly because its baroque street plan presented a perfect geometric grid for calculations and measurements."In his book, Augen am Himmel, Wolfgang Schreyer wrote:
Frampol was chosen as an experimental object, because test bombers, flying at low speed, weren't endangered by AA fire. Also, the centrally placed town hall was an ideal orientation point for the crews. We watched possibility of orientation after visible signs, and also the size of village, what guaranteed that bombs nevertheless fall down on Frampol. From one side it should make easier the note of probe, from second side it should confirm the efficiency of used bombs.
The directives issued to the Luftwaffe for the Polish Campaign were to prevent the Polish Air Force from influencing the ground battles or attacking German territory. In addition, it was to support the advance of German ground forces through direct tactical and indirect air support with attacks against Polish mobilisation centres and thus delay an orderly Polish strategic concentration of forces and to deny mobility for Polish reinforcements through the destruction of strategic Polish rail routes.
Preparations were made for a concentrated attack by all bomber forces against targets in Warsaw. However, the operation was cancelled, according to Polish professor Tomasz Szarota due to bad weather conditions, while German author Horst Boog claims it was possibly due to Roosevelt's plea to avoid civilian casualties; according to Boog the bombing of military and industrial targets within the Warsaw residential area called Praga was prohibited. Polish reports from the beginning of September note strafing of civilians by German attacks and bombing of cemeteries and marked hospitals, and indiscriminate attacks on fleeing civilians which according to Szarota was a direct violation of the Hague Convention. Warsaw was first attacked by German ground forces on 9 September and was put under siege on 13 September. German author Boog claims that with the arrival of German ground forces, the situation of Warsaw changed; under the Hague Convention, the city could be legitimately attacked as it was a defended city in the front line that refused calls to surrender.
The bombing of the rail network, crossroads, and troop concentrations played havoc on Polish mobilisation, while attacks upon civilian and military targets in towns and cities disrupted command and control by wrecking the antiquated Polish signal network. Over a period of a few days, Luftwaffe numerical and technological superiority took its toll on the Polish Air Force. Polish Air Force bases across Poland were also subjected to Luftwaffe bombing from 1 September 1939.
On 13 September, following orders of the Commander-in-Chief of the Luftwaffe to launch an attack on Warsaw's Jewish Quarter, justified as being for unspecified crimes committed against German soldiers but probably in response to a recent defeat by Polish ground troops, and intended as a terror attack, 183 bomber sorties were flown with 50:50 load of high explosive and incendiary bombs, reportedly set the Jewish Quarter ablaze. On 22 September, Wolfram von Richthofen messaged, "Urgently request exploitation of last opportunity for large-scale experiment as devastation terror raid... Every effort will be made to eradicate Warsaw completely". His request was rejected. However, Adolf Hitler issued an order to prevent civilians from leaving the city and to continue with the bombing, which he thought would encourage Polish surrender.
On 14 September, the French Air attaché in Warsaw reported to Paris, "the German Air Force acted in accordance to the international laws of war and bombed only targets of military nature. Therefore, there is no reason for French retorsions." That day – the Jewish New Year – the Germans concentrated again on the Warsaw's Jewish population, bombing the Jewish quarter and targeting synagogues. According to professor Szarota the report was inaccurate – as its author Armengaud didn't know about the most barbaric bombings like those in Wieluń or Kamieniec, left Poland on 12 September, and was motivated by his personal political goal to avoid French involvement in the war, in addition the report published in 1948 rather than in 1939.
File:Bundesarchiv Bild 141-0763, Warschau, Brände.jpg|thumb|Warsaw burning after a German bombing of the city. The Luftwaffe air campaign resulted in the deaths of an estimated 20,000 – 25,000 civilians.
Three days later, Warsaw was surrounded by the Wehrmacht, and hundreds of thousands of leaflets were dropped on the city, instructing citizens to evacuate the city pending a possible bomber attack. On 25 September the Luftwaffe flew 1,150 sorties and dropped 560 tonnes of high explosive and 72 tonnes of incendiaries.
To conserve the strength of the bomber units for the upcoming Western campaign, the modern He 111 bombers were replaced by Ju 52 transports using "worse than primitive methods" for the bombing. Due to prevailing strong winds they achieved poor accuracy, even causing some casualties to besieging German troops.
The only Polish raid against a target in Germany was executed by PZL.23 Karaś light bombers against a factory in Ohlau. The Polish air force left Poland on 18 September 1939 due to the Soviet attack on 17 September 1939, and imminent capture of the Polish airstrips and aircraft stationed in eastern parts of Poland. There was no exception; even Pursuit Brigade, an organic part of the defences of the Polish capital, Warsaw, was transferred to Lublin, one week into the war.
There happened also a non-planned single bombing of the Free City of Danzig. On 7 September, at about 11 PM, a Polish Lublin R.XIII G seaplane was flying over the city, on a mission to attack the German Schleswig-Holstein battleship. However, the vessel had already left the city, so the seaplane flew over the center of Danzig, where it bombed and opened fire on the German troops celebrating the capitulation of the Polish garrison of Westerplatte.