What is the greatest cause of war? Some of the most common causes of war are religious differences, territory, oppression, and self-defense (Khan). Alliances are formed between countries to avoid war. Countries enter into alliances believing that this will protect their sovereignty and the security of their nation (HamzaU). In some ways this can be beneficial, but it can also cause harm. Alliances can create suspicion and fear between two nations, causing war. Three of the many wars caused by alliances are the Vietnam War, World War I, and World War II. Alliances caused and affected these wars in many ways. The Vietnam War began on November 1, 1955 and ended on April 30, 1955. 1975. It lasted 19 and a half years. Fighting took place in Vietnam for decades before the Vietnam War began. The Vietnamese suffered under French colonial rule for nearly six decades when Japan invaded parts of Vietnam in 1940 (Rosenberg). Although most fighting took place in Vietnam, the war also spread to neighboring Laos and Cambodia in the early 1970s (Szczepanski). The causes of the Vietnam War arose from the symptoms, components and consequences of the Cold War (Trueman). During the Vietnam War, the Republic of South Vietnam and the Democratic Republic of North Vietnam had many allies. More than forty countries provided assistance and military support, they also sent men, money and equipment to support the government and army of Vietnam. In addition, a number of other countries sent small contingents of medical, transportation, construction and other experts (Friedmen). The Vietnam War was a very costly war. This not only affected those who participated in the battles, but I...... middle of paper ......ar I. .Rosmantiz, Klaus. Second World War. .Szczepanski, Kallie. Facts about Vietnam. .Theatlantic.com. Second World War. October 30, 2011. Archived from the original on March 28, 2014. Trueman, Chris. Cause of World War II. 2000. April 2, 2014.—. the causes of the Vietnam War. 2000. Wilde, Robert. First World War: the great alliances. .Second World War. World War 2. 2014. .