Total war
The commitment to the doctrine of the short war was a continuing handicap for the Germans; neither plans nor state of mind were adjusted to the idea of a long war until the failure of the Operation Barbarossa. A major strategic defeat in the Battle of Moscow forced Speer as armaments minister to nationalise German war production and eliminate the worst inefficiencies.

Canada: In Canada early use of the term concerned whether or not the country was committing enough to mobilising its resources, rather than whether or not to target civilians of the enemy countries.  During the early days of the Second World War, whether or not Canada was committed to a "total war effort" was point of partisan political debate between the governing Liberals and the opposition Conservatives.  The Conservatives elected as their national leader Arthur Meighen, who had been the cabinet minister responsible for implementing conscription during the First World War, and advocated for conscription again.  Prime Minister W.L. Mackenzie King argued that Canada could still be said to have a "total war effort" without conscription, and delivered nationally broadcast speeches to this effect 1942.  Meighen failed to win his seat in by-election in 1942, and the issue subsided for a short time.  But eventually, national conscription was introduced in Canada in 1944, as well as dramatically increased taxation, another symbol of the "total war effort".

Soviet Union: The Soviet Union (USSR) was a command economy which already had an economic and legal system allowing the economy and society to be redirected into fighting a total war. The transportation of factories and whole labour forces east of the Urals as the Germans advanced across the USSR in 1941 was an impressive feat of planning. Only those factories which were useful for war production were moved because of the total war commitment of the Soviet government.
The Eastern Front of the European Theatre of World War II encompassed the conflict in central and eastern Europe from 22 June 1941, to 9 May 1945. It was the largest theatre of war in history in terms of numbers of soldiers, equipment and casualties and was notorious for its unprecedented ferocity, destruction, and immense loss of life (see World War II casualties). The fighting involved millions of German, Hungarian, Romanian and Soviet troops along a broad front hundreds of kilometres long. It was by far the deadliest single theatre of World War II. Scholars now believe that at most 27 million Soviet citizens died during the war, including at least 8.7 million soldiers who fell in battle against Hitler's armies or died in POW camps. Millions of civilians died from starvation, exposure, atrocities, and massacres. The Axis lost over 5 million soldiers in the east as well as many thousands of civilians.
During the Battle of Stalingrad, newly built T-34 tanks were driven—unpainted because of a paint shortage—from the factory floor straight to the front. This came to symbolise the USSR's commitment to a policy of total war.

United States: The United States underwent an unprecedented mobilisation of national resources for the Second World War, creating a military-industrial complex that still exists. Although the United States was not in danger of an existential attack, the national sense after Pearl Harbor was to use all the nation's resources to defeat Germany and Japan. Most non-essential activities were rationed, prohibited or restrained, and most of the fit unmarried young men were drafted. There was little urgency before 1940, when the collapse of France ended the Phoney War and revealed urgent needs. Nevertheless, President Franklin Roosevelt moved to first solidify public opinion before acting. In 1940 the first peacetime draft was instituted, along with Lend-Lease programs to aid the British, and covert aid was passed to the Chinese as well.
American public opinion was still opposed to involvement in the problems of Europe and Asia, however. In 1941, the Soviet Union became the latest nation to be invaded, and the U.S. gave its aid as well. American ships began defending aid convoys to the Allied nations against submarine attacks, and a total trade embargo against the Empire of Japan was instituted to deny its military the raw materials its factories and military forces required to continue its offensive actions in China.
In late 1941, Japan's Army-dominated government decided to seize by military force the strategic resources of South-East Asia and Indonesia since the Western powers would not give Japan these goods by trade. Planning for this action included surprise attacks on American and British forces in Hong Kong, the Philippines, Malaya, and the U.S. naval base and warships at Pearl Harbor. In response to these attacks, the UK and U.S. declared war the next day. Nazi Germany declared war on the U.S. a few days later, along with Fascist Italy; the U.S. found itself fully involved in a second world war.
As the United States began to gear up for a major war, information and propaganda efforts were set in motion. Civilians (including children) were encouraged to take part in fat, grease, and scrap metal collection drives. Many factories making non-essential goods retooled for war production. Levels of industrial productivity previously unheard of were attained during the war; multi-thousand-ton convoy ships were routinely built in a month and a half, and tanks poured out of the former automobile factories. Within a few years of the U.S. entry into the Second World War, nearly every man without children fit for service, between 18 and 30, was conscripted into the military "for the duration" of the conflict, and unprecedented numbers of women took up jobs previously held by them. Strict systems of rationing of consumer staples were introduced to redirect productive capacity to war needs.
Previously untouched sections of the nation mobilised for the war effort. Academics became technocrats; home-makers became bomb-makers (massive numbers of women worked in industry during the war); union leaders and businessmen became commanders in the massive armies of production. The great scientific communities of the United States were mobilised as never before, and mathematicians, doctors, engineers, and chemists turned their minds to the problems ahead of them.
By the war's end, a multitude of advances had been made in medicine, physics, engineering, and the other sciences. This included the efforts of the theoretical physicists working at the Los Alamos National Laboratory on the Manhattan Project, which led to the Trinity nuclear test and thus brought about the Atomic Age.
In the war, the United States lost 407,316 military personnel, but had managed to avoid the extensive level of damage to civilian and industrial infrastructure that other participants suffered. The U.S. emerged as one of the two superpowers after the war.

Unconditional surrender: Actually Dresden was a mass of munitions works, an intact government centre, and a key transportation point to the East. It is now none of these things.
After the United States entered World War II, Franklin D. Roosevelt declared at Casablanca conference to the other Allies and the press that unconditional surrender was the objective of the war against the Axis Powers of Germany, Italy, and Japan. Prior to this declaration, the individual regimes of the Axis Powers could have negotiated an armistice similar to that at the end of World War I and then a conditional surrender when they perceived that the war was lost.
The unconditional surrender of the major Axis powers caused a legal problem at the post-war Nuremberg Trials, because the trials appeared to be in conflict with Articles 63 and 64 of the Geneva Convention of 1929. Usually if such trials are held, they would be held under the auspices of the defeated power's own legal system as happened with some of the minor Axis powers, for example in the post World War II Romanian People's Tribunals. To circumvent this, the Allies argued that the major war criminals were captured after the end of the war, so they were not prisoners of war and the Geneva Conventions did not cover them. Further, the collapse of the Axis regimes created a legal condition of total defeat (debellatio) so the provisions of the 1907 Hague Convention over military occupation were not applicable.

Post-World War II: Since the end of World War II, no industrial nation has fought such a large, decisive war. This is likely due to the availability of nuclear weapons, whose destructive power and quick deployment render a full mobilisation of a country's resources such as in World War II logistically impractical and strategically irrelevant.
By the end of the 1950s, the ideological stand-off of the Cold War between the Western world and the Soviet Union had resulted in thousands of nuclear weapons being aimed by each side at the other. Strategically, the equal balance of destructive power possessed by each side manifests in the doctrine of mutually assured destruction (MAD), which determines that a nuclear attack by one superpower would result in a nuclear counter-strike by the other. This would result in hundreds of millions of deaths in a world where, in words widely attributed to Nikita Khrushchev, "The living will envy the dead".

During the Cold War, the two superpowers sought to avoid open conflict between their respective forces, as both sides recognised that such a clash could very easily escalate, and quickly involve nuclear weapons. Instead, the superpowers fought each other through their involvement in proxy wars, military buildups, and diplomatic standoffs.
In the case of proxy wars, each superpower supported its respective allies in conflicts with forces aligned with the other superpower, such as in the Vietnam War and the Soviet invasion of Afghanistan.