Total war
Characteristics: Total war is a concept that has been extensively studied by scholars of conflict and war. One of the most notable contributions to this field of research is the work of Stig Förster, who has identified four dimensions of total war: total purposes, total methods, total mobilisation, and total control. Tiziano Peccia has built upon Förster's work by adding a fifth dimension of "total change." Peccia argues that total war not only has a profound impact on the outcome of the conflict but also produces significant changes in the political, cultural, economic, and social realms beyond the end of the conflict. As Peccia puts it, "total war is an earthquake that has the world as its epicenter."
The four dimensions of total war identified by Förster are:
1) Total purposes: The aim of continuous growth of the power of the parties involved and hegemonic visions.
2) Total methods: Similar and common methodologies among countries that intend to increase their spheres of influence.
3) Total mobilisation: Inclusion in the conflict of parties not traditionally involved, such as women and children or individuals who are not part of the armed bodies.
4) Total control: Multisectoral centralisation of the powers and orchestration of the activities of the countries in a small circle of dictators or oligarchs, with cross-functional control over education and culture, media/propaganda, economic, and political activities.
Peccia's contribution of "total change" adds to this framework by emphasising the long-term effects of total war on society.
5) Total change: This includes changes in social attitudes, cultural norms, and political structures, as well as economic and technological developments.
In Peccia's view, total war not only transforms the military and political landscape but also has far-reaching and long-time implications for society as a whole.
Actions that may characterise the post-19th century concept of total war include:

Strategic bombing, as during World War II, the Korean War, and the Vietnam War (Operations Barrel Roll, Rolling Thunder and Linebacker II)
Blockade and sieging of population centres, as with the Allied blockade of Germany and the Siege of Leningrad during the First and Second World Wars
Scorched earth policy, as with the March to the Sea during the American Civil War and the Japanese "Three Alls Policy" during the Second Sino-Japanese War
Commerce raiding, tonnage war, and unrestricted submarine warfare, as with privateering, the German U-boat campaigns of the First and Second World Wars, and the United States submarine campaign against Japan during World War II
Collective punishment, pacification operations, and reprisals against populations deemed hostile, as with the execution and deportation of suspected Communards following the fall of the 1871 Paris Commune or the German reprisal policy targeting resistance movements, insurgents, and Untermenschen such as in France (e.g. Maillé massacre) and Poland during World War II
Industrial warfare, as with all belligerents in their respective home fronts during World War I and World War II
The use of civilians and prisoners of war as forced labour for military operations, as with Japan, USSR and Germany's massive use of forced labourers of other nations during World War II (see Slavery in Japan and forced labour under German rule during World War II)
Giving no quarter (i.e. take no prisoners), as with Hitler's Commando Order during World War II

Background: The phrase "total war" can be traced back to the 1935 publication of German general Erich Ludendorff's World War I memoir, Der totale Krieg ("The total war"). Some authors extend the concept back as far as classic work of Carl von Clausewitz, On War, as "absoluter Krieg" (absolute war), even though he did not use the term; others interpret Clausewitz differently.  Total war also describes the French "guerre à outrance" during the Franco-Prussian War.
In his 24 December 1864 letter to his chief of staff during the American Civil War, Union general William Tecumseh Sherman wrote the Union was "not only fighting hostile armies, but a hostile people, and must make old and young, rich and poor, feel the hard hand of war, as well as their organized armies," defending Sherman's March to the Sea, the operation that inflicted widespread destruction of infrastructure in Georgia.
United States Air Force General Curtis LeMay updated the concept for the nuclear age. In 1949, he first proposed that a total war in the nuclear age would consist of delivering the entire nuclear arsenal in a single overwhelming blow, going as far as "killing a nation".

History: 

Middle Ages: Written by academics at Eastern Michigan University, the Cengage Advantage Books: World History textbook claims that while total war "is traditionally associated with the two global wars of the twentieth century... it would seem that instances of total war predate the twentieth century." They write:

As an aggressor nation, the ancient Mongols, no less than the modern Nazis, practiced total war against an enemy by organizing all available resources, including military personnel, non-combatant workers, intelligence, transport, money, and provisions.

18th and 19th centuries: 

Europe: In his book, The First Total War: Napoleon's Europe and the Birth of Warfare as We Know it, David A Bell, a French History professor at Princeton University argues that the French Revolutionary Wars introduced to mainland Europe some of the first concepts of total war, such as mass conscription. He claims that the new republic found itself threatened by a powerful coalition of European nations and used the entire nation's resources in an unprecedented war effort that included levée en masse (mass conscription). By 23 August 1793, the French front line forces grew to some 800,000 with a total of 1.5 million in all services—the first time an army in excess of a million had been mobilised in Western history:

From this moment until such time as its enemies shall have been driven from the soil of the Republic all Frenchmen are in permanent requisition for the services of the armies. The young men shall fight; the married men shall forge arms and transport provisions; the women shall make tents and clothes and shall serve in the hospitals; the children shall turn old lint into linen; the old men shall betake themselves to the public squares in order to arouse the courage of the warriors and preach hatred of kings and the unity of the Republic.

During the Russian campaign of 1812 the Russians retreated while destroying infrastructure and agriculture in order to effectively hamper the French and strip them of adequate supplies. In the campaign of 1813, Allied forces in the German theatre alone amounted to nearly one million whilst two years later in the Hundred Days a French decree called for the total mobilisation of some 2.5 million men (though at most a fifth of this was managed by the time of the French defeat at Waterloo). During the prolonged Peninsular War from 1808 to 1814 some 300,000 French troops were kept permanently occupied by, in addition to several hundred thousand Spanish, Portuguese and British regulars, an enormous and sustained guerrilla insurgency—ultimately French deaths would amount to 300,000 in the Peninsular War alone.
The Franco-Prussian War was fought in breach of the recently signed Geneva Convention of 1864, when "European opinion increasingly expected that civilians and soldiers should be treated humanely in war".

North America: The Sullivan Expedition of 1779 was an example of total warfare. As Native American and Loyalist forces massacred American farmers, killed livestock and burned buildings in remote frontier areas, General George Washington sent General John Sullivan with 4,000 troops to seek "the total destruction and devastation of their settlements" in upstate New York. There was only one small battle as the expedition devastated "14 towns and most flourishing crops of corn."  The Native Americans escaped to Canada where the British fed them; they remained there after the war.
Sherman's March to the Sea in the American Civil War—from 15 November 1864, through 21 December 1864—is sometimes considered to be an example of total war, for which Sherman used the term hard war. Some historians challenge this designation, as Sherman's campaign assaulted primarily military targets and Sherman ordered his men to spare civilian homes.

20th century: 

World War I: 

Air Warfare: Bombing civilians from the air was adopted as a strategy for the first time in World War I, and a leading advocate of this strategy was Peter Strasser "Leader of Airships" (Führer der Luftschiffe; F.d.L.). Strasser, who was chief commander of German Imperial Navy Zeppelins during World War I, the main force operating German strategic bombing across Europe and the UK, saw bombing of civilians as well as military targets as an essential element of total war. He argued that causing civilian casualties and damaging domestic infrastructure served both as propaganda and as a means of diverting resources from the front line.

We who strike the enemy where his heart beats have been slandered as 'baby killers' ... Nowadays, there is no such animal as a noncombatant. Modern warfare is total warfare.

Propaganda: One of the features of total war in Britain was the use of government propaganda posters to divert all attention to the war on the home front. Posters were used to influence public opinion about what to eat and what occupations to take, and to change the attitude of support towards the war effort. Even music halls were used as propaganda, with propaganda songs aimed at recruitment.