War

War is an armed conflict between states, organizations, or relatively large groups of people, characterised by lethal violence between combatants or against civilians. Other terms for war, which often serve as euphemisms, include armed conflict, hostilities, and police action (note). War is contrasted with peace, which is usually defined as the absence of war. A common perception of war is a series of military campaigns between at least two opposing sides involving a dispute over sovereignty, territory, resources, religion or a host of other issues. A war to liberate an occupied country is sometimes characterised as a "war of liberation", while a war between internal elements of the same state may constitute a civil war.

History of War
"Warfare is the greatest affair of state, the basis of life and death, the Tao to survival or extinction. It must be thoroughly pondered and analyzed."---The Art of War by Sun Tzu. War seems as old as human society, and certainly features prominently in the recorded histories of state-cultures. The earliest city states and empires in Mesopotamia became the first to employ standing armies. Before this, it was typical for the army to consist entirely or mostly of militia. Organization and structure has since been central to warfare, as illustrated by the success of highly disciplined troops of the Roman Empire. As well as organizational change, technology has played a central role in the evolution of warfare. Armies with iron weapons easily defeated armies armed with bronze. Inventions created for warfare play an important role in advances in other fields, but modern technology has greatly increased the potential cost and destruction of war. The study of warfare is known as military history.

Morality of War
Throughout history, war has been the source of serious moral questions. Although many ancient nations and some more modern ones viewed war as noble, over the sweep of history concerns about the morality of war have gradually increased. Today war is generally seen as undesirable and, by some, morally problematic, although many view war, or at least the preparation and readiness and willingness to engage in war, as a necessary precursor to the defense of their country against aggressors. Pacifists believe that war is inherently immoral and that no war should ever be fought. This position was passionately defended by the Indian leader Mahatma Ghandi. The negative view of war has not always been held as widely as it is today. Many thinkers, such as Heinrich von Treitschke saw war as humanity's highest activity where courage, honor, and ability were more necessary than in any other endeavour. At the outbreak of World War I the writer Thomas Mann wrote, "Is not peace an element of civil corruption and war a purification, a liberation, an enormous hope?" This attitude has been embraced by societies from Sparta and Rome in the ancient world to the fascist states of the 1930s. The defeat and repudiation of the fascist states and their militarism in the Second World War, the shock of the first use of nuclear weapons and increased respect for the sanctity of individual life, as enshrined in the concept of human rights, for example, have contributed to the current view of war. Today, some see only just wars as legitimate, and believe that it is the goal of organizations such as the United Nations to unite the world against wars of unjust aggression. Others believe that the United Nations has no more moral advantage than that of a sovereign country.

Limitations
At times throughout history, societies have attempted to limit the cost of war by formalizing it in some way. Limitations on the targeting of civilians, what type of weapons can be used, and when combat is allowed have all fallen under these rules in different conflicts. Total war is the modern term for the targeting of civilians and the mobilization of an entire society; when every member of the society has to contribute to the war effort. While culture, law, and religion have all been factors in causing wars, they have also acted as restraints at times. In some cultures, for example, conflicts have been highly ritualized to limit actual loss of life. In modern times, increasing international attention has been paid to peacefully resolving conflicts which lead to war. The United Nations is the latest and most comprehensive attempt to, as stated in the preamble of the U.N. Charter, "save succeeding generations from the scourge of war." A number of treaties regulate warfare, collectively referred to as the laws of war. The most pervasive of those are the Geneva Conventions, the earliest of which began to take effect in the mid 1800s. Treaty signing has since been a part of international diplomacy, and too many treaties to mention in this scant article have been signed. A couple of examples are: Resolutions of the Geneva International Conference, Geneva, 26 October-29 October 1863 and Geneva Convention relative to the Treatment of Prisoners of War, 75 U.N.T.S. 135, entered into force 21 October 1950. It must be noted that in war such treaties are generally thrown to one side if they interfere with the vital interests of either side; some have criticised such conventions as simply providing a fig leaf for the inhuman practice of war. By only illegalising "war against the rules", it is alleged, such treaties and conventions, in effect, sanction certain types of war.

Redefining "war" for legal reasons
Sometimes the term "war" is restricted by legal definition to those conflicts where one or both belligerents have formally declared war. This has resulted in wars (in the sense defined in the introduction to this article) without formal declaration and combatants who officially choose terms other than "war," such as: For example, the United States Government referred to the Korean War as a "police action", and the British Government was very careful to use the term "armed conflict" instead of "war" during the Falklands War in 1982 to comply with the letter of international law. Sometimes the term "war" will not be used in order to circumvent national constitutions which restrict the power of the executive to wage war without the agreement of other branches of government.
 * "armed conflict";
 * "state aggression by armed force";
 * "police action";
 * "crime against international peace".

Causes of war
There is great debate over why wars happen, even when most people do not want them to. Representatives of many different academic disciplines have attempted to explain war.

Historical theories
Historians tend to be reluctant to look for sweeping explanations for all wars. A. J. P. Taylor famously described wars as being like traffic accidents. There are some conditions and situations that make them more likely but there can be no system for predicting where and when each one will occur. Social scientists criticize this approach arguing that at the beginning of every war some leader makes a conscious decision and that they cannot be seen as purely accidental.

Psychological theories
Psychologists such as E.F.M. Durban and John Bowlby have argued that human beings, especially men, are inherently violent. While this violence is repressed in normal society it needs the occasional outlet provided by war. This combines with other notions, such as displacement where a person transfers their grievances into bias and hatred against other ethnic groups, nations, or ideologies. While these theories may have some explanatory value about why wars occur, they do not explain when or how they occur. In addition, they raise the question why there are sometimes long periods of peace and other eras of unending war. If the innate psychology of the human mind is unchanging, these variations are inconsistent. A solution adapted to this problem by militarists such as Franz Alexander is that peace does not really exist. Periods that are seen as peaceful are actually periods of preparation for a later war or when war is suppressed by a state of great power, such as the Pax Britannica. If war is innate to human nature, as is presupposed by many psychological theories, then there is little hope of ever escaping it. One alternative is to argue that war is only, or almost only, a male activity and if human leadership was in female hands wars would not occur. This theory has played an important role in modern feminism. Critics, of course, point to various examples of female political leaders who had no qualms about using military force, such as Margaret Thatcher or Indira Gandhi. Other psychologists have argued that while human temperament allows wars to occur, they only do so when mentally unbalanced men are in control of a nation. This extreme school of thought argues leaders that seek war such as Napoleon, Hitler, and Stalin were mentally abnormal. A distinct branch of the psychological theories of war are the arguments based on evolutionary psychology. This school tends to see war as an extension of animal behaviour, such as territoriality and competition. However, while war has a natural cause, the development of technology has accelerated human destructiveness to a level that is irrational and damaging to the species. We have the same instincts of a chimpanzee but overwhelmingly more power. The earliest advocate of this theory was Konrad Lorenz. These theories have been criticized by scholars such as John G. Kennedy, who argue that the organized, sustained war of humans differs more than just technologically from the territorial fights between animals. In his fictional book Nineteen-Eighty-Four, George Orwell talks about war being used as one of many ways to distract people. War inspires fear and hate among the people of a nation, and gives them a 'legitimate' enemy upon whom they can focus this fear and hate. Thus the people are prevented from seeing that their true enemy is in fact their own repressive government. By this theory, war is another 'opiate of the masses' by which a state controls its people and prevents revolution.

Anthropological theories
Several anthropologists take a very different view of war. They see it as fundamentally cultural, learned by nurture rather than nature. Thus if human societies could be reformed, war would disappear. To this school the acceptance of war is inculcated into each of us by the religious, ideological, and nationalistic surroundings in which we live. Many anthropologists also see no links between various forms of violence. They see the fighting of animals, the skirmishes of hunter-gatherer tribes, and the organized warfare of modern societies as distinct phenomena each with their own causes. Theorists such as Ashley Montagu emphasize the top down nature of war, that almost all wars are begun not by popular pressure but by the whims of leaders and that these leaders also work to maintain a system of ideological justifications for war.

Sociological theories
Sociology has long been very concerned with the origins of war, and many thousands of theories have been advanced, many of them contradictory. Some use detailed formulas taking into account hundreds of demographic and economic values to predict when and where wars will break out. The statistical analysis of war was pioneered by Lewis Fry Richardson following World War I. More recent databases of wars and armed conflict have been assembled by the Correlates of War Project, Peter Brecke and the Uppsala Department of Peace and Conflict Research. So far none of these formulas have successfully predicted the outbreak of future conflicts. A detailed study by Michael Haas found that no single variable has a strong correlation to the occurrence of wars. One correlation that has found much support is that states that are democracies do not go to war with each other, an idea known as the democratic peace theory. Many sociologists have attempted to divide wars into types to get better correlations, but this has also produced mixed results. Data looked at by R.J. Rummel has found that civil wars and foreign wars are very different in origin, but Jonathan Wilkenfield using different data found just the opposite. Sociology has thus divided into a number of schools. One based on the works of Eckart Kehr and Hans-Ulrich Wehler sees war as the product of domestic conditions, with only the target of aggression being determined by international realities. Thus World War I was not a product of international disputes, secret treaties, or the balance of power but a product of the economic, social, and political situation within each of the states involved. This differs from the traditional approach of Carl von Clausewitz and Leopold von Ranke that argue it is the decisions of statesmen and the geopolitical situation that leads to war.

Malthusian theories
Pope Urban in 1095, on the eve of the First Crusade, wrote, "For this land which you now inhabit, shut in on all sides by the sea and the mountain peaks, is too narrow for your large population; it scarcely furnishes food enough for its cultivators. Hence it is that you murder and devour one another, that you wage wars, and that many among you perish in civil strife. Let hatred, therefore, depart from among you; let your quarrels end. Enter upon the road to the Holy Sepulcher; wrest that land from a wicked race, and subject it to yourselves." This is one of the earliest expressions of what has come to be called the Malthusian theory of war, in which wars are caused by expanding populations and limited resources. Thomas Malthus (1766 - 1834) wrote that populations always increase until they are limited by war, disease, or famine. This theory is thought by Malthusians to account for the relative decrease in wars during the past fifty years, especially in the developed world, where advances in agriculture have made it possible to support a much larger population than was formerly the case, and where birth control has dramatically slowed the increase in population.

Information theories
A popular new approach is to look at the role of information in the outbreak of wars. This theory, advanced by scholars of international relations such as Geoffrey Blainey, argues that all wars are based on a lack of information. If both sides at the outset knew the result neither would fight, the loser would merely surrender and avoid the cost in lives and infrastructure that a war would cause. This is based on the notion that wars are reciprocal, that all wars require both a decision to attack and also a decision to resist attack. This notion is generally agreed to by almost all scholars of war since Clausewitz. This notion is made harder to accept because it is far more common to study the cause of wars rather than events that failed to cause wars, and wars are far more memorable. However, throughout history there are as many invasions and annexations that did not lead to a war, such as the U.S.-led invasion of Haiti in 1994, the Nazi invasions of Austria and Czechoslovakia preceding the Second World War, and the annexation of the Baltic states by the Soviet Union in 1940. On the other hand, Finland's decision to resist a similar Soviet aggression in 1939 led to the Winter War. The leaders of these nations chose not to resist as they saw the potential benefits being not worth the loss of life and destruction such resistance would cause. Lack of information may not only be to who wins in the immediate future. The Norwegian decision to resist the Nazi invasion was taken with the certain knowledge that Norway would fall. The Norwegians did not know whether the German domination would be permanent and also felt that noble resistance would win them favour with the Allies and a position at the peace settlement in the event of an Allied victory. If in 1940 it had been known with certainty the Germans would dominate central Europe for many decades, it is unlikely the Norwegians would have resisted. If it had been known for certainty that the Third Reich would collapse after only a few years of war, the Nazis would not have launched the invasion at all. This theory is predicated on the notion that the outcome of wars is not randomly determined, but fully determined on factors such as doctrine, economies, and power. While purely random events, such as storms or the right person dying at the right time, might have had some effect on history, these only influence a single battle or slightly alter the outcome of a war, but would not mean the difference between victory and defeat. There are two main objectives in the gathering of intelligence. The first is to find out the ability of an enemy, the second their intent. In theory to have enough information to prevent all wars both need to be fully known. The Argentinean dictatorship knew that the United Kingdom had the ability to defeat them, but their intelligence failed them on the question of whether the British would use their power to resist the annexation of the Falklands. The American decision to enter the Vietnam War was made with the full knowledge that the communist forces would resist them, but did not believe that the guerrillas had the capability to long oppose American forces. One major difficulty is that in a conflict of interests, some deception or at least not telling everything is a standard tactical component on both sides. If you think that you can convince the opponent that you will fight, the opponent might desist. For example, Sweden made efforts to deceive Nazi Germany that it would resist an attack fiercely partly by playing on the myth of Aryan superiority, and by making sure that Hermann Göring only saw elite troops in action, often dressed up as regular soldiers, when he came to visit.

Marxist theories
The economic theories also form a part of the Marxist theory of war, which argues that all war grows out of the class war. It sees wars as imperial ventures to enhance the power of the ruling class and divide the proletariat of the world by pitting them against each other for contrived ideals such as nationalism or religion. Wars are a natural outgrowth of the free market and class system, and will not disappear until a world revolution occurs.

Types of war and warfare
Smaller armed conflicts are often called riots, rebellions, coups, etc.

When one country sends armed forces to another, allegedly to restore order or prevent genocide or other crimes against humanity, or to support a legally recognized government against insurgency, that country sometimes refers to it as a police action. This usage is not always recognized as valid, however, particularly by those who do not accept the connotations of the term.

"Conventional warfare" describes either:

(Compare with unconventional warfare and nuclear warfare.)
 * A war between nation-states
 * War where nuclear or biological weapons are not used.
 * A war where the forces in conflict belong to the same country or empire or other political entity is known as a civil war.

Asymmetrical warfare is a conflict between two populations of drastically different levels of military mechanization. This type of war often results in guerrilla tactics. The Israeli-Palestinian conflict is a common example of asymmetrical warfare. Terrorism can be considered an extreme form of asymmetrical warfare. Military action produces a very small percentage of air pollution emissions. Intentional air pollution in combat is one of a collection of techniques collectively called chemical warfare. Poison gas as a chemical weapon was principally used during World War I, and resulted in an estimated 91,198 deaths and 1,205,655 injuries. Various treaties have sought to ban its further use. Non-lethal chemical weapons, such as tear gas and pepper spray, are widely used.

Geographic Warfare
The terrain over which a war is fought has a big impact on the type of combat which takes place. This in turn means that soldiers have to be trained to fight in a specific type of terrain. These include:
 * Arctic warfare
 * Ski warfare
 * Desert warfare
 * Jungle warfare
 * Naval warfare or Aquatic warfare
 * Sub-aquatic warfare
 * Mountain warfare (sometimes called alpine warfare)
 * Urban warfare
 * Air warfare
 * Space warfare