The Holy Roman Empire was nominally created from the ruins of the Western Roman Empire during the so-called Dark Ages of European history. Charlemagne, a Frankish King in the early ninth century, was crowned Holy Roman Emperor in 800 C.E.

The Protestant Reformation began in Europe in the early sixteenth century. Specifically it can be traced to 1517, when the German monk nailed his 95 Theses to the door of a Church in Germany. Lutheranism was the first major religion of the Protestant Reformation, followed shortly by Calvinism (John Calvin), Zwinglism (Ulrich Zwingli), and Anglicanism (Henry VIII).

An armistice is a temporary halt in conflict during a war; it is often followed by the signing of a peace treaty, but when two sides cannot reach agreement it may simply be a temporary break before the fighting resumes. The policy of allowing an enemy or a rival to achieve certain gains in the hope that they will then be appeased is called "appeasement." A smaller state or nation that is dependent on a larger state for protection is called a "satellite state." A vote by the people to directly decide the outcome of an issue is called either a "plebiscite" or a "referendum."

The Kellogg-Briand Pact was signed in 1928 by most of the powerful nations of the world at the time. Signed between World War One and World War Two, it was meant to prevent a future outbreak of world war. Considering that World War Two broke out a decade later, and that Japan invaded Manchuria in 1931, it can hardly be seen as a success, yet it was an important step in the history of civilization, because it was the first major attempt to renounce warfare as a means of foreign policy.

The term, "Apartheid," refers to a period in South African history when the government actively promoted and sponsored discrimination and segregation on the basis of race. It ended in 1990.

The Hundred Years’ War was a series of conflicts waged between England and France from 1337 to 1453. The war was primarily fought for control of the Kingdom of France and ended with English finances exhausted, with civil war brewing as the majority of France remained outside of English control.

The Crusades is the name given to a series of military campaigns waged by the nations of Western Europe between 1095 and 1487 C.E. The primary goal was to retake Jerusalem and the Holy Land for Christianity from the Islamic Empires that held sway there at the time, but some crusades were declared against heretic Christians in Europe.

The Industrial Revolution began in England towards the end of the eighteenth century and eventually spread to Europe and the United States. It was the primary reason why England was able to dominate so effectively the economic stage during the nineteenth century.

Jonas Salk invented the world’s first polio vaccine in 1953. Prior to the invention of this vaccine polio had crippled and killed millions of people throughout human history.

The Industrial Revolution is generally considered to have begun in England and shortly thereafter in Northern and Western Europe towards the end of the eighteenth century. The pace of change dramatically accelerated in the nineteenth century. The Industrial Revolution was a period of massive economic and social upheaval in Europe and the United States. On the back of new technologies, in particular the creation of the factory system, a whole new labor system arose, and both the working and middle classes grew in number.