Wars have been fought from time immemorial. No society can claim to have no war history.
Among the causes of war the opposite claims on land ore territory is main one. The first world war was fought because Germany invaded Belgium in 1914 and then France and then occupied them. The second world war started in 1939 when Hitler started annexing East European countries.
The second main cause of war in modern times is efforts of powerful countries to control central production of oil production centers of oils, gas and metals.
The third major cause of war has been religion though not so much in our age. We know how many holy or religious wars were fought between the Christians and muslims about 900 years ago called the Crusades.
The fourth great cause of war has been racial. Some nations begin thinking that their race is superior to all other races. They develop and promote racial feelings within their countries. As a result they begin fighting against other races and nations. The superior racial feelings of western and partly of east European nations today are causing tremendous and great pain and injury to other nations which is not a good thing.
War is an extended state of violent, large-scale divergence involving two or more groups of nation. When and how war originated in humans is a highly contentious topic. Some judge it began only on the subject of five millennia ago, with the rise of the earliest states; afterwards war "broaden to peaceful hunter-gatherers and agriculturalists".
The basic incentive, of course, is readiness to wage war, but motivations may be analyzed specifically. Motivations for war may be dissimilar for those ordering the war than for that responsibility the war. For a state to put on trial a war it must have the hold up of its leadership, its armed forces, and the population. For example, in the third Panic War, Rome's leaders may have wished to make war with Carthage for the reason of annihilating a resurgent rival; the army may have wished to make war with Carthage to use the great occasion for rob while leveling the city of Carthage.
But the Roman people may encompass tolerated the war with Carthage on explanation of the deionization of the Carthaginians in well-liked culture, since there had been rumors of child give up. Since many people are involved, a war may get a life of its own -- from the confluences of numerous unlike motivations.
I agree with all guests on this site. My point is war may be occurred over territory, natural resources and economic.