Editing World War II (section)

=== Western Europe (1940–1941) ===
{{Main|Western Front (World War II)}}
[[File:WWIIEuropeMay40.gif|thumb|upright=1.4|German advance into Belgium and Northern France, 10 May{{snd}}4 June 1940, sweeping past the [[Maginot Line]] (shown in dark red)]]

In April 1940, [[Operation Weserübung|Germany invaded Denmark and Norway]] to protect shipments of [[Swedish iron-ore industry during World War II|iron ore from Sweden]], which the Allies were [[Operation Wilfred|attempting to cut off]].<ref>{{Harvnb|Murray|Millett|2001|pp=57–63}}.</ref> [[German invasion of Denmark (1940)|Denmark capitulated after six hours]], and [[Norwegian campaign|despite Allied support]], Norway was conquered within two months.{{sfn|Commager|2004|p=9}} [[Norway Debate|British discontent over the Norwegian campaign]] led to the resignation of Prime Minister [[Neville Chamberlain]], who was replaced by [[Winston Churchill]] on 10{{spaces}}May 1940.{{sfn|Reynolds|2006|p=76}}

On the same day, Germany [[Battle of France|launched an offensive against France]]. To circumvent the strong [[Maginot Line]] fortifications on the Franco-German border, Germany directed its attack at the neutral nations of [[German invasion of Belgium (1940)|Belgium]], [[German invasion of the Netherlands|the Netherlands]], and [[German invasion of Luxembourg|Luxembourg]].{{sfn|Evans|2008|pp=122–123}} The Germans carried out a flanking manoeuvre through the [[Ardennes]] region,{{sfn|Keegan|1997|pp=59–60}} which was mistakenly perceived by the Allies as an impenetrable natural barrier against armoured vehicles.{{sfn|Regan|2004|p=152}}{{sfn|Liddell Hart|1977|p=48}} By successfully implementing new ''[[Blitzkrieg]]'' tactics, the ''Wehrmacht'' rapidly advanced to the Channel and cut off the Allied forces in Belgium, trapping the bulk of the Allied armies in a cauldron on the Franco-Belgian border near Lille. The United Kingdom was able [[Dunkirk evacuation|to evacuate a significant number of Allied troops]] from the continent by early June, although they had to abandon almost all their equipment.{{sfn|Keegan|1997|pp=66–67}}

On 10 June, [[Italian invasion of France|Italy invaded France]], declaring war on both France and the United Kingdom.{{sfn|Overy|Wheatcroft|1999|p=207}} The Germans turned south against the weakened French army, and [[Paris in World War II|Paris]] fell to them on 14{{spaces}}June. Eight days later [[Armistice of 22 June 1940|France signed an armistice with Germany]]; it was divided into [[German military administration in occupied France during World War II|German]] and [[Italian occupation of France|Italian occupation zones]],{{sfn|Umbreit|1991|p=311}} and an unoccupied [[rump state]] under the [[Vichy France|Vichy Regime]], which, though officially neutral, was generally aligned with Germany. France kept its fleet, which [[Attack on Mers-el-Kébir|the United Kingdom attacked]] on 3{{spaces}}July in an attempt to prevent its seizure by Germany.{{sfn|Brown|2004|p=198}}

The air [[Battle of Britain]]{{sfn|Keegan|1997|p=[{{GBurl|id=TF8kcx9hTssC|p=72}} 72]}} began in early July with [[Kanalkampf|Luftwaffe attacks on shipping and harbours]].<ref name="Murray_BoB">{{harvnb|Murray|1983|loc=[https://www.ibiblio.org/hyperwar/AAF/AAF-Luftwaffe/AAF-Luftwaffe-2.html#cn70 The Battle of Britain].}}</ref> The [[Adlertag|German campaign for air superiority]] started in August but its failure to defeat [[RAF Fighter Command]] forced the indefinite postponement of the [[Operation Sea Lion|proposed German invasion of Britain]]. The German [[strategic bombing]] offensive intensified with night attacks on London and other cities in [[the Blitz]], but largely ended in May 1941{{sfn|Dear|Foot|2001|pp=108–109}} after failing to significantly disrupt the British war effort.{{r|Murray_BoB}}

Using newly captured French ports, the German Navy [[Battle of the Atlantic#'The Happy Time' (June 1940 – February 1941)|enjoyed success]] against an over-extended [[Royal Navy]], using [[U-boat]]s against British shipping [[Battle of the Atlantic|in the Atlantic]].<ref>{{Harvnb|Goldstein|2004|p=35}}</ref> The British [[Home Fleet]] scored a significant victory on 27{{spaces}}May 1941 by [[Last battle of Bismarck|sinking the German battleship ''Bismarck'']].<ref>{{Harvnb|Steury|1987|p=209}}; {{Harvnb|Zetterling|Tamelander|2009|p=282}}.</ref>

In November 1939, the United States was assisting China and the Western Allies, and had amended the [[Neutrality Acts of the 1930s|Neutrality Act]] to allow "[[Cash and carry (World War II)|cash and carry]]" purchases by the Allies.{{sfn|Overy|Wheatcroft|1999|pp=328–330}} In 1940, following the German capture of Paris, the size of the [[United States Navy]] was [[Two-Ocean Navy Act|significantly increased]]. In September the United States further agreed to a [[Destroyers-for-bases deal|trade of American destroyers for British bases]].{{sfn|Maingot|1994|p=52}} Still, a large majority of the American public continued to oppose any direct military intervention in the conflict well into 1941.{{sfn|Cantril|1940|p=390}} In December 1940, Roosevelt accused Hitler of planning world conquest and ruled out any negotiations as useless, calling for the United States to become an "[[Arsenal of Democracy|arsenal of democracy]]" and promoting [[Lend-Lease]] programmes of military and humanitarian aid to support the British war effort; Lend-Lease was later extended to the other Allies, including the Soviet Union after it was [[Operation Barbarossa|invaded]] by Germany.<ref name="ibiblio_1940">{{Cite web |title=Major international events of 1940, with explanation |url=https://www.ibiblio.org/pha/events/1940.html |url-status=live |archive-url=https://web.archive.org/web/20130525060313/https://www.ibiblio.org/pha/events/1940.html |archive-date=25 May 2013 |publisher=Ibiblio.org}}</ref> The United States started strategic planning to prepare for a full-scale offensive against Germany.<ref>{{Cite web |last=Skinner Watson |first=Mark |title=Coordination With Britain |url=https://www.ibiblio.org/hyperwar/USA/USA-WD-Plans/USA-WD-Plans-12.html |url-status=live |archive-url=https://web.archive.org/web/20130430001549/https://www.ibiblio.org/hyperwar/USA/USA-WD-Plans/USA-WD-Plans-12.html |archive-date=30 April 2013 |access-date=13 May 2013 |website=US Army in WWII – Chief of Staff: Prewar Plans and Operations}}</ref>

At the end of September 1940, the [[Tripartite Pact]] formally united Japan, Italy, and Germany as the [[Axis powers]]. The Tripartite Pact stipulated that any country—with the exception of the Soviet Union—that attacked any Axis Power would be forced to go to war against all three.{{Sfn|Bilhartz|Elliott|2007|p=179}} The Axis expanded in November 1940 when [[Kingdom of Hungary (1920–1946)|Hungary]], [[Slovak Republic (1939–1945)|Slovakia]], and [[Kingdom of Romania|Romania]] joined.{{Sfn|Dear|Foot|2001|p=877}} [[Romania in World War II|Romania]] and [[Hungary in World War II|Hungary]] later made major contributions to the Axis war against the Soviet Union, in Romania's case partially to recapture [[Soviet occupation of Bessarabia and Northern Bukovina|territory ceded to the Soviet Union]].{{Sfn|Dear|Foot|2001|pp=745–746}}