There are many factors that lead to countries going to war. Some of these factors include imperialism, nationalism, and militarism. Imperialism is the desire for land. There are many reasons why countries want or have wanted more land, including economic reasons. When a country gets more land, it becomes easier for that country to access certain resources that are needed to make more products. The country also will have a new marketplace where its businesses can sell their products.
Nationalism is pride in one’s country. There have been times when countries have gone to war, in part, because they believe they have been insulted by the actions of another country. Before World War II, Germany felt it was mistreated by the terms of the Versailles Treaty, which ended World War I. This contributed to Adolf Hitler's rise to power. In other cases, a country feels its way of life is superior to another country’s way of life. Thus, the former country goes to war with the latter, in part, to spread its way of life. This can also includes the forced spread of religious values and practices.
Militarism is when a country builds up its military. When a country builds up its military, this may be a signal that it is planning to go to war. This is what occurred before World War I. As Germany built up its military, France and Great Britain did the same thing.
Sometimes war may occur over a specific issue. For example, the Civil War in the United States was fought over the issues of slavery and whether the states should have more power than the federal government.
The effects of war are very significant. There are the human impacts. When a soldier is killed in battle, that loss permanently affects the family and community of the soldier. The resulting pain and emptiness are always present for these families. Soldiers who are injured may have their lives altered permanently. They may lose the ability to walk, or they may deal with the psychological effects of being involved in a war.
There are economic consequences also. The money spent on a war means that there is less money available for investment. The money spent on a war takes away money that could be used to invest in the economy. Oftentimes, farmland is damaged as a result of the fighting. It may take years for that land to recover.