The Reconquista was a seemingly endless conflict that permeated Spanish society. The Islamic conquests of the 8th Century pushed Catholic Spaniards into a tiny spit of land in Northern Spain. Were it not for the help from a number of other Christian nations, Catholic Spaniards would have, in all likelihood, been unable to win the conflict. Muslims were not fully ousted from Spain until 1492.

World War I was a conflict between the Allies (the United Kingdom, Russia, France, and later Japan, Italy, and the United States) and the Central Powers (primarily Germany, Austria-Hungry, and the Ottoman Empire). The Allies were formed out of the Triple Entente, which was a pact formed in 1907 between the United Kingdom, France, and Russia in order to limit political and military rivalry between those nations. Of course the war involved a variety of countries across the world and occasionally participants and alliances would change. Italy initially fought for the Central Powers until it switched sides in 1915. Russia left the war entirely due to internal political turmoil and made peace with the Central Powers. The United States did not enter the war on the side of the Allies until 1917.

At the beginning of the 20^th Century there was a lot of political and economic turmoil in Russia, due to the policies of the tsar, humiliating military defeats, and poor economic activity. This eventually led to the Russian Revolution, when the tsar was overthrown by the Bolsheviks. While this was going on Russia was involved in World War I, where it had not been faring well fighting the Central Powers. The new government wanted to remove Russia from the conflict to focus on internal issues and negotiated the Treaty of Brest-Litovsk with the Central Powers in 1918. The treaty called for Russia to forfeit some of its land and also to pay Germany for damages in exchange for peace. The terms of the treaty were essentially rendered irrelevant following the defeat of the Central Powers.

The Opium Wars were fought from 1839 to 1842 and from 1856 to 1860. The conflicts stemmed from the fact that China was imported very little from European nations until Great Britain started to sell opium to the Chinese. People became addicted to the drug and demanded more while society began to deteriorate. China outlawed opium and then attempted to cut off its foreign trade and so Great Britain took military action to ensure that trade would continue. The first war resulted in China agreeing to continue to trade with Great Britain and to open up some ports just for trade. The second war came about when Britain wanted to trade opium again even though China had already made the opium trade illegal and resulted in China opening more trading ports and giving more freedom to foreigners that visited China. 

Arthur Wellesley was born in 1769 and entered the military at age 18 and quickly rose through the ranks and eventually became a general while fighting Napoleon. He was promote to Field Marshall in 1813 after a victory and after the first war was given the title of Duke of Wellington and also became Ambassador to France. When Napoleon came back to try and recapture his throne Wellington led the British forces and fought along with the Prussians to defeat Napoleon at Waterloo. After that victory he went on to have a distinguished career in politics, including serving twice as Prime Minster. Wellington is revered as one of the finest military commanders in British history.

The assassination of Ernst vom Rath was the most proximate cause of the pogrom of Kristallnacht (also known as The Night of Broken Glass). Kristallnacht took place over two days in April 1938.

The main and proximate cause of the American entrance into World War II in 1941 was the bombing of the American naval base at Pearl Harbor by the Japanese. This event sparked outrage in the U.S and resulted in Roosevelt making the decision to enter the war on the side of its allies. Although inspired by Japanese aggression in the Pacific, the entry of the United States into the war is considered a major turning point in the European theatre of World War II.

Charles I attempted to force Scotland to join the Anglican church so the whole of his kingdom would follow one religion. While such action could be said to have direct and negative influence on the Scottish clan system, the issue really lay in the attempt to enforce Anglicanism on the population, so this is the best answer.

India was Britain's primary source of goods as well as people for work and soldiers. Taking Egypt would mean that the British would have to sail around the southern tip of Africa in order to reach India rather than take the shorter route through Egypt. Thus severely harming the British War effort.

The Battle of Wagram took place in the War of the Fifth Coalition, and cemented the idea of total French superiority in the mind of Napoleon thus leading to his decision to invade Russia.