World War II

By the end of this lesson, students will be able to:

• Account for how technology and innovation shaped the course of the Second World War and the twentieth century (Skill 4.B; LO K).
• Account for KC-4.1.III.B: how Germany's Blitzkrieg in Europe, combined with Japan's attacks in Asia and the Pacific, produced early Axis victories.
• Account for KC-4.1.III.C: how American and British industrial, scientific, and technological power, cooperative military efforts under leaders such as Winston Churchill, civilian resistance, and the all-out commitment of the Soviet Union were critical to the Allied victories.
• Account for KC-4.3.II.C: how military technologies enabled industrialized warfare, genocide, nuclear proliferation, and the prospect of global nuclear war.
• Contextualize the Second World War's military technologies within the broader continuity of industrial warfare from 1914-1918 and the postwar nuclear strategic order (Skill 4.B in direct practice).

Topic 8.8 covers the Second World War's military and technological course from the German invasion of Poland on 1 September 1939 to the Japanese surrender on 2 September 1945. KC-4.1.III.B captures the early phase: Germany's Blitzkrieg and Japan's attacks in Asia and the Pacific produced early Axis victories. KC-4.1.III.C captures the strategic reversal: American and British industrial-scientific power, cooperative military leadership, civilian resistance, and the Soviet all-out commitment produced the Allied victories. KC-4.3.II.C captures the technological dimension: military technologies enabled industrialized warfare, genocide, nuclear proliferation, and the prospect of global nuclear war.

Blitzkrieg and the early Axis victories (KC-4.1.III.B). Blitzkrieg ("lightning war") combined four elements that the German army had developed in the late 1930s: concentrated armored thrusts in Panzer divisions, close air support from the Luftwaffe (especially the Junkers Ju 87 Stuka dive bomber), motorized infantry that could keep pace with the armor, and radio-coordinated command that integrated the three combat arms in real time. The doctrine had been theorized in the interwar period (J. F. C. Fuller and Basil Liddell Hart in Britain, Heinz Guderian in Germany, Mikhail Tukhachevsky's "deep operations" theory in the Soviet Union before his execution in the 1937 purges); the German army applied it in 1939 and 1940 against opponents whose doctrine and equipment remained closer to 1918 patterns.

The Polish campaign of 1-28 September 1939 illustrated the doctrine in operation. German forces, supported from the east by the Soviet invasion of 17 September 1939 (under the secret protocol of the Molotov-Ribbentrop Pact, covered in Topic 8.7), defeated the Polish army in approximately four weeks. Warsaw fell on 27 September 1939; the Polish government went into exile in London. The Western campaign of 10 May to 25 June 1940 was more dramatic: German Panzer divisions broke through the Ardennes (which the French command had treated as impassable for armor) on 13-15 May 1940, reached the English Channel on 20 May 1940, and trapped the British Expeditionary Force and the French First Army against the coast. The Dunkirk evacuation of 26 May to 4 June 1940 returned roughly 338,000 Allied troops to Britain; France signed an armistice on 22 June 1940. The European war that the French and British had expected to fight in Belgium had ended in six weeks.

The Battle of Britain (10 July to 31 October 1940) was the first major Allied operational success. The Royal Air Force, equipped with the Supermarine Spitfire and the Hawker Hurricane, supported by the world's first integrated air-defense system (the "Dowding System" of radar stations, plotting rooms, and ground control), defeated the Luftwaffe's daylight bombing campaign against southeast England. The Luftwaffe lost approximately 1,887 aircraft against approximately 1,547 RAF losses; the planned German invasion of Britain (Operation Sea Lion) was indefinitely postponed on 17 September 1940. Radar — covered in more depth below — was the principal British technological advantage; the Battle of Britain demonstrated its operational value.

Operation Barbarossa, the German invasion of the Soviet Union from 22 June 1941, was the largest land campaign in human history. Three German army groups (North, Center, South) totaling approximately 3 million men, supported by Romanian, Hungarian, Italian, and Slovak forces, advanced into Soviet territory along a front of approximately 1,800 miles. By December 1941 German forces had reached the outskirts of Leningrad, the outer suburbs of Moscow, and the Crimea. The Soviet counter-offensive at Moscow on 5-6 December 1941 (under Marshal Zhukov, with reinforcements from the Far Eastern theater that Soviet intelligence had cleared after the Tokyo report from Richard Sorge) stopped the German advance. The Pacific war began the following day with the Japanese attack on Pearl Harbor on 7 December 1941; Germany declared war on the United States on 11 December 1941; the global war that the Atlantic Charter of 14 August 1941 had prefigured had arrived.

The Allied strategic reversal (KC-4.1.III.C). The Allied victory rested on four reinforcing factors that KC-4.1.III.C identifies. The first was the industrial output of the United States. American war production from 1942 to 1945 substantially exceeded Axis production: the United States produced approximately 297,000 aircraft, approximately 88,000 tanks, approximately 65,000 landing craft, and approximately 41 billion rounds of small-arms ammunition; the Liberty Ship program produced approximately 2,710 standardized cargo vessels averaging 42 days build time. The second was British scientific and operational innovation, anchored in the Tizard Mission of August-October 1940 (which transferred the cavity magnetron, the Frisch-Peierls atomic memorandum, and other British scientific work to American laboratories), the Ultra programme at Bletchley Park (which read German Enigma traffic from 1940 onward), and operational research that systematically applied scientific method to military problems (convoy size, depth-charge settings, bombing accuracy).

The third factor was cooperative military leadership. Winston Churchill (Prime Minister of the United Kingdom from 10 May 1940), Franklin D. Roosevelt (President of the United States from March 1933), and Joseph Stalin (Soviet leader from the late 1920s) coordinated Allied strategy through the Atlantic Charter of 14 August 1941, the Washington Conference (Arcadia, December 1941-January 1942), the Casablanca Conference of January 1943 (which established the unconditional-surrender doctrine), the Tehran Conference of November-December 1943 (which committed the Western Allies to a 1944 cross-Channel invasion and the Soviet Union to entry into the Pacific war after Germany's defeat), and the Yalta and Potsdam conferences of February and July-August 1945 that organized the postwar settlement. The Combined Chiefs of Staff (American and British military leadership) coordinated the Anglo-American strategic effort from January 1942; the Eastern Front strategic coordination ran through Stalin and the Soviet Stavka rather than through the Combined Chiefs.

The fourth factor was the all-out Soviet commitment. The Soviet Union mobilized approximately 34 million people into its armed forces over the course of the war and suffered approximately 27 million total deaths (military and civilian combined), the highest absolute figure of any belligerent. The relocation of Soviet industry east of the Urals from autumn 1941 onward — approximately 1,500 factories were dismantled, transported, and reassembled in the Volga, Urals, and Siberian regions — sustained Soviet munitions production through the worst of the German occupation. The Soviet T-34 tank (entered service June 1940) combined heavy armor, a high-velocity 76mm gun, and reliable diesel engineering; it was produced in approximately 84,000 units between 1940 and 1958 and outclassed contemporary German Panzer III and Panzer IV designs. The eastern-front Soviet offensives at Stalingrad (August 1942-February 1943), Kursk (July 1943, the largest tank battle in history), and Operation Bagration (June-August 1944, which destroyed German Army Group Center) ground down the Wehrmacht at a sustained rate that Western front operations did not match.

Civilian resistance in occupied Europe added a fifth dimension. Yugoslav Partisans under Josip Broz Tito tied down substantial Axis forces in the Balkans from 1941 onward; the French Resistance and the Special Operations Executive (a British organization formed in July 1940 to "set Europe ablaze") coordinated sabotage and intelligence; the Polish Home Army (Armia Krajowa) staged the Warsaw Uprising of 1 August to 2 October 1944; the Greek, Italian, Norwegian, Dutch, Belgian, Czech, and Soviet partisan and resistance movements imposed sustained costs on the German occupation administration and provided substantial intelligence to Allied military planners. The cost in civilian lives was enormous: German anti-partisan reprisals (Lidice in June 1942, Oradour-sur-Glane in June 1944, the Greek village massacres) and the broader pattern of occupation violence killed civilians on a scale that Topic 8.9 will examine in connection with the Holocaust.

Military technology and the long century (KC-4.3.II.C). Military technologies enabled industrialized warfare, genocide, nuclear proliferation, and the prospect of global nuclear war. The principal Second World War military technologies fall into five families. Radar (radio direction and ranging) had been developed in parallel by Britain, Germany, and the United States in the 1930s; the British Chain Home network (operational from 1939) provided the integrated early-warning system that the Battle of Britain depended on; airborne radar from 1941 onward and centimetric radar (the cavity magnetron) from 1940 transformed the Battle of the Atlantic by allowing Allied aircraft to detect surfaced U-boats at night and in poor weather. Code-breaking and signals intelligence reached unprecedented operational scale: the Polish Cipher Bureau's pre-war work on the German Enigma machine (transferred to British and French intelligence in July 1939) anchored the Bletchley Park Ultra programme that read German naval, air, and army traffic from 1940 onward; the American MAGIC programme read Japanese diplomatic traffic; the Battle of Midway on 4-7 June 1942 turned in part on American advance knowledge of Japanese plans through MAGIC.

The third technology family was strategic bombing. The Anglo-American Combined Bomber Offensive from 1942 to 1945 dropped approximately 2.7 million tons of bombs on Germany and German-occupied Europe; the United States Army Air Forces favored daylight precision bombing while RAF Bomber Command favored area bombing at night. Civilian deaths from strategic bombing of Germany reached approximately 305,000-600,000 (estimates vary); the firebombing of Hamburg (24-30 July 1943, "Operation Gomorrah") killed approximately 37,000 civilians; the bombing of Dresden (13-15 February 1945) killed approximately 25,000 civilians; the United States firebombing of Tokyo on 9-10 March 1945 killed approximately 100,000 civilians in a single night. The fourth technology family was ballistic and cruise missiles. The German V-1 cruise missile (operational from June 1944) and V-2 ballistic missile (operational from September 1944) were the first deployed weapons of their respective categories; approximately 9,521 V-1s and approximately 3,172 V-2s were launched against Britain, Belgium, and the Netherlands, killing approximately 9,000 people. The V-2 program (under Wernher von Braun at Peenemuende) anchored the postwar American and Soviet rocket programs after Operation Paperclip and Soviet recruitment of German engineers.

The fifth and most consequential technology family was nuclear weapons. The Manhattan Project, established under American military authority in August 1942 with substantial British scientific cooperation (the Quebec Agreement of August 1943), produced the first atomic weapons. The Trinity test on 16 July 1945 in the Jornada del Muerto desert of New Mexico demonstrated the implosion-design plutonium weapon. The atomic bomb over Hiroshima on 6 August 1945 (a uranium-gun-type "Little Boy" device, dropped from the B-29 Enola Gay under Colonel Paul Tibbets) killed approximately 70,000-80,000 people instantly and approximately 140,000 by the end of 1945. The atomic bomb over Nagasaki on 9 August 1945 (an implosion-type "Fat Man" plutonium device) killed approximately 40,000 people instantly and approximately 70,000 by the end of 1945. Japan announced its surrender on 15 August 1945; the formal instrument of surrender was signed on 2 September 1945 aboard the USS Missouri in Tokyo Bay. The Soviet atomic-weapons project (under Igor Kurchatov) tested its first device on 29 August 1949 (RDS-1, "First Lightning"); the postwar nuclear-strategic order that Topic 9.6 will examine had begun.

The Skill 4.B argument. Topic 8.8's suggested skill is 4.B (Contextualization: account for the way a particular historical development or process fits within a broader context). The skill applies in two principal ways. First, students should contextualize the Second World War's industrial scale within the longer history of industrialized warfare that began with the First World War (Topic 8.2): the cumulative pattern of mass mobilization, civilian targeting, and technological escalation across both wars. Second, students should contextualize the Manhattan Project and the atomic bombings within the broader twentieth-century strategic order: the postwar nuclear-strategic competition that organized the Cold War, the eventual extension of nuclear capability to the United Kingdom (1952), France (1960), the People's Republic of China (1964), India (1974), Israel (likely 1960s-1970s), Pakistan (1998), and North Korea (2006), and the long-running international debate over nuclear non-proliferation that the Treaty on the Non-Proliferation of Nuclear Weapons (1968) institutionalized.

Three sources framing the war: the cooperative Allied war aims, the speech that anchored British civilian resistance, and the announcement that opened the nuclear era.

1. (Causation, Skill 4.B) Contextualize the German Blitzkrieg doctrine of 1939-1941 within the longer history of industrialized warfare since 1914. What was new in 1939, and what was a continuation of trends from the First World War?
2. (Causation) Account for KC-4.1.III.B: how did Germany's Blitzkrieg in Europe and Japan's attacks in Asia and the Pacific produce early Axis victories? Cite the Polish, Western, and Pacific campaigns and the operational features that distinguished Axis from Allied military doctrine in 1939-1941.
3. (Causation) Account for KC-4.1.III.C: identify the four reinforcing factors that produced the Allied strategic reversal from 1942 onward. Which factor is most decisive on which front?
4. (Causation, Skill 4.B) Contextualize the Manhattan Project and the atomic bombings of Hiroshima and Nagasaki within the broader twentieth-century strategic order. What postwar developments did the Manhattan Project foreshadow?
5. (Causation) Account for KC-4.3.II.C: how did military technologies enable industrialized warfare, genocide, nuclear proliferation, and the prospect of global nuclear war? Cite specific examples from radar, code-breaking, strategic bombing, ballistic missiles, and nuclear weapons.

Draft alignment — pending educator review. AP European History codes correspond to the official College Board Course and Exam Description (Effective Fall 2023, V.1). Statements below are paraphrased in the CountryReports voice; refer to the College Board's published CED for verbatim wording.