World War II

===Advances in technology and its application===
{{Main|Technology during World War II}}
[[File:Bundesarchiv Bild 146-1978-Anh.026-01, Peenemünde, V2 beim Start.jpg|thumb|A [[V-2 rocket]] launched from a fixed site in [[Peenemünde]], 21 June 1943]]

Aircraft were used for [[Reconnaissance aircraft|reconnaissance]], as [[fighter aircraft|fighters]], [[bomber]]s, and [[close air support|ground-support]], and each role developed considerably. Innovations included [[airlift]] (the capability to quickly move limited high-priority supplies, equipment, and personnel);<ref name="EncWWII_76">{{Harvnb|Tucker|Roberts|2004|p=76}}.</ref> and [[strategic bombing]] (the bombing of enemy industrial and population centres to destroy the enemy's ability to wage war).<ref>{{Harvnb|Levine|1992|p=227}}.</ref> [[Anti-aircraft warfare|Anti-aircraft weaponry]] also advanced, including defences such as [[radar]] and surface-to-air artillery, in particular the introduction of the [[proximity fuze]]. The use of the [[jet aircraft]] was pioneered and led to jets becoming standard in air forces worldwide.<ref>{{Harvnb|Klavans|Di Benedetto|Prudom|1997}}; {{Harvnb|Ward|2010|pp=247–251}}.</ref>

Advances were made in nearly every aspect of [[naval warfare]], most notably with [[aircraft carrier]]s and [[submarine]]s. Although [[Aeronautics|aeronautical]] warfare had relatively little success at the start of the war, [[Battle of Taranto|actions at Taranto]], [[Attack on Pearl Harbor|Pearl Harbor]], and the [[Battle of the Coral Sea|Coral Sea]] established the carrier as the dominant capital ship (in place of the battleship).<ref name="EncWWII_163">{{Harvnb|Tucker|Roberts|2004|p=163}}.</ref><ref>{{Cite book|last1= Bishop|first1= Chris|last2= Chant|first2=Chris|title=Aircraft Carriers: The World's Greatest Naval Vessels and Their Aircraft|page= 7|publisher= Silverdale Books|year= 2004|isbn=978-1-84509-079-1|location= Wigston, Leics}}</ref><ref>{{Cite book|last1=Chenoweth|first1=H. Avery|last2= Nihart|first2= Brooke|title= Semper Fi: The Definitive Illustrated History of the U.S. Marines|publisher= Main Street|year= 2005|isbn= 978-1-4027-3099-3|page= 180|location= New York}}</ref> In the Atlantic, [[escort carrier]]s became a vital part of Allied convoys, increasing the effective protection radius and helping to close the [[Mid-Atlantic gap]].<ref>{{Harvnb|Sumner|Baker|2001|p=25}}.</ref> Carriers were also more economical than [[battleship]]s due to the relatively low cost of aircraft<ref>{{Harvnb|Hearn|2007|p=14}}.</ref> and because they are not required to be as heavily armoured.<ref>{{Harvnb|Gardiner|Brown|2004|p=52}}.</ref> Submarines, which had proved to be an effective weapon during the [[World War I|First World War]],<ref name="Bur&Ryd 1995 15">{{Harvnb|Burcher|Rydill|1995|p=15}}.</ref> were expected by all combatants to be important in the second. The British focused development on [[Anti-submarine warfare|anti-submarine]] [[anti-submarine weapon|weaponry]] and tactics, such as [[sonar]] and convoys, while Germany focused on improving its offensive capability, with designs such as the [[Type VII submarine]] and [[Wolfpack (naval tactic)|wolfpack]] tactics.<ref name="Bur&Ryd 1995 16">{{Harvnb|Burcher|Rydill|1995|p=16}}.</ref>{{Better source needed|reason=this is arguably a reference in passing – the book is about the design of submarines and deals with this fairly superficially. Also reference in article only points to a review of this book.|date=July 2020}} Gradually, improving Allied technologies such as the [[Leigh Light]], [[Hedgehog (weapon)|Hedgehog]], [[Squid (weapon)|Squid]], and [[Mark 24 mine|homing torpedoes]] proved effective against German submarines.<ref>{{Cite journal |title= Impact of technology on the defeat of the U-boat September 1939 – May 1943 |journal=  IEE Proceedings - Science, Measurement and Technology|date=September 1994 |volume=141 |issue=5 |pages=343–355 |doi=10.1049/ip-smt:19949918 |last1=Burns |first1=R. W. }}</ref>

[[File:Trinity device readied.jpg|thumb|Nuclear ''Gadget'' being raised to the top of the detonation "shot tower", at [[Alamogordo Bombing and Gunnery Range|Alamogordo Bombing Range]]; [[Trinity (nuclear test)|Trinity nuclear test]], [[New Mexico]], July 1945]]
[[Land warfare]] changed from the static frontlines of [[trench warfare]] of World War&nbsp;I, which had relied on improved [[artillery]] that outmatched the speed of both [[infantry]] and [[cavalry]], to increased mobility and [[combined arms]]. The [[tank]], which had been used predominantly for infantry support in the First World War, had evolved into the primary weapon.<ref name="EncWWII_125">{{Harvnb|Tucker|Roberts|2004|p=125}}.</ref> In the late 1930s, tank design was considerably more advanced than it had been during World War{{nbsp}}I,<ref>{{Cite book|last= Dupuy|first= Trevor Nevitt|title= The Evolution of Weapons and Warfare|publisher=[[Jane's Information Group]]|isbn= 978-0-7106-0123-0|year= 1982|page= 231}}</ref> and [[Tanks in World War II|advances continued throughout the war]] with increases in speed, armour and firepower.<ref>{{cite web |title=The Vital Role Of Tanks In The Second World War |url= https://www.iwm.org.uk/history/the-vital-role-of-tanks-in-the-second-world-war |access-date=5 April 2022 |website=Imperial War Museums |language=en |archive-date=25 March 2022 |archive-url=https://web.archive.org/web/20220325104344/https://www.iwm.org.uk/history/the-vital-role-of-tanks-in-the-second-world-war |url-status=live }}</ref><ref>{{Cite journal |last1=Castaldi |first1=Carolina |last2=Fontana |first2=Roberto |last3=Nuvolari |first3=Alessandro |date=1 August 2009 |title='Chariots of fire': the evolution of tank technology, 1915–1945 |journal=Journal of Evolutionary Economics |language=en |volume=19 |issue=4 |pages=545–566 |doi=10.1007/s00191-009-0141-0 |s2cid=36789517 |issn=1432-1386 |doi-access=free |hdl=10419/89322 |hdl-access=free }}</ref> At the start of the war, most commanders thought enemy tanks should be met by tanks with superior specifications.<ref name="EncWWII_108">{{Harvnb|Tucker|Roberts|2004|p=108}}.</ref> This idea was challenged by the poor performance of the relatively light early tank guns against armour, and German doctrine of avoiding tank-versus-tank combat. This, along with Germany's use of combined arms, were among the key elements of their highly successful blitzkrieg tactics across Poland and France.<ref name="EncWWII_125" /> Many means of [[Anti-tank warfare|destroying tanks]], including [[Indirect fire|indirect artillery]], [[anti-tank gun]]s (both towed and [[Self-propelled artillery|self-propelled]]), [[Anti-tank mine|mines]], short-ranged infantry antitank weapons, and other tanks were used.<ref name="EncWWII_108" /> Even with large-scale mechanisation, infantry remained the backbone of all forces,<ref name="EncWWII_734">{{Harvnb|Tucker|Roberts|2004|p=734}}.</ref> and throughout the war, most infantry were equipped similarly to World War&nbsp;I.<ref name="Comp_221">{{Harvnb|Cowley|Parker|2001|p=221}}.</ref> The portable machine gun spread, a notable example being the German [[MG 34]], and various [[submachine gun]]s which were suited to [[close combat]] in urban and jungle settings.<ref name="Comp_221" /> The [[assault rifle]], a late war development incorporating many features of the rifle and submachine gun, became the standard post-war infantry weapon for most armed forces.<ref>{{cite web |title=The AK-47: the worlds favourite killing machine |publisher=controlarms.org |first1=Oliver |last1=Sprague |first2=Hugh |last2=Griffiths |url=https://www.amnesty.org/en/documents/act30/011/2006/en/ |access-date=14 November 2009 |year=2006 |format=PDF |page=1 |archive-url=https://web.archive.org/web/20181228130914/https://www.amnesty.org/en/documents/act30/011/2006/en/ |archive-date=28 December 2018 |url-status=live}}</ref>

Most major belligerents attempted to solve the problems of complexity and security involved in using large [[codebook]]s for [[cryptography]] by designing [[cipher]]ing machines, the most well-known being the German [[Enigma machine]].<ref>{{Harvnb|Ratcliff|2006|p=11}}.</ref> Development of [[SIGINT]] (''sig''nals ''int''elligence) and [[cryptanalysis]] enabled the countering process of decryption. Notable examples were the Allied decryption of [[Japanese naval codes]]<ref name=Schoenherr>{{cite web|access-date=15 November 2009|archive-date=9 May 2008|archive-url=https://web.archive.org/web/20080509054959/https://history.sandiego.edu/gen/WW2Timeline/espionage.htm|first=Steven|last=Schoenherr|publisher=History Department at the University of San Diego|title=Code Breaking in World War I|url=https://history.sandiego.edu/gen/WW2Timeline/espionage.htm|url-status=dead|year=2007}}</ref> and British [[Ultra (cryptography)|Ultra]], a [[Bombe#The British Bombe|pioneering method]] for decoding Enigma that benefited from information given to the United Kingdom by the [[Cipher Bureau (Poland)#Gift to allies|Polish Cipher Bureau]], which had been decoding early versions of Enigma before the war.<ref>{{cite news |author=Macintyre, Ben |date=10 December 2010 |title=Bravery of thousands of Poles was vital in securing victory |page=27 |work=The Times |location=London |id={{Gale|IF0504159516}}}}</ref> Another component of [[military intelligence]] was [[deception]], which the Allies used to great effect in operations such as [[Operation Mincemeat|Mincemeat]] and [[Operation Bodyguard|Bodyguard]].<ref name=Schoenherr /><ref>{{cite web|title=Deception for Defense of Information Systems: Analogies from Conventional Warfare|url=https://www.au.af.mil/au/awc/awcgate/nps/mildec.htm|first1=Neil C.|last1=Rowe|first2=Hy|last2=Rothstein|work=Departments of Computer Science and Defense Analysis U.S. Naval Postgraduate School|publisher=Air University|access-date=15 November 2009|archive-url=https://web.archive.org/web/20101123031630/https://www.au.af.mil/au/awc/awcgate/nps/mildec.htm|archive-date=23 November 2010|url-status=live}}</ref>

Other technological and engineering feats achieved during, or as a result of, the war include the world's first programmable computers ([[Z3 (computer)|Z3]], [[Colossus computer|Colossus]], and [[ENIAC]]), [[V-1 flying bomb|guided missiles]] and [[V-2 rocket|modern rockets]], the [[Manhattan Project]]'s development of [[nuclear weapon]]s, [[operations research]], the development of [[Mulberry harbour|artificial harbours]], and [[Operation Pluto|oil pipelines under the English Channel]].<ref>{{Cite web |title=World War – II |url=https://www.insightsonindia.com/world-history/world-war-i/world-war-ii/ |website=InsightsIAS |language=en-US |access-date=17 September 2022 |archive-date=11 July 2022 |archive-url=https://web.archive.org/web/20220711080947/https://www.insightsonindia.com/world-history/world-war-i/world-war-ii/ |url-status=live }}</ref> [[Penicillin]] was first [[History of penicillin|developed, mass-produced, and used]] during the war.<ref>{{cite web|archive-url= https://web.archive.org/web/20190628035235/https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/flemingpenicillin.html|archive-date=28 June 2019|url= https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/flemingpenicillin.html |title=Discovery and Development of Penicillin: International Historic Chemical Landmark|location=Washington, DC|publisher=[[American Chemical Society]]|access-date=15 July 2019}}</ref>