Nationalism is an ideology that emphasizes the importance of the nation-state and the belief that a nation should be independent and self-governing.

The French Revolution is often considered the catalyst for the rise of nationalism in Europe in the 19th century, as it led to the spread of ideas such as liberty, equality, and fraternity, which inspired people to seek self-determination and national independence.

The assassination of Archduke Franz Ferdinand of Austria was the immediate cause of World War I, as it led to a chain of events that resulted in the outbreak of war.

Austria-Hungary was the first country to declare war in World War I, on July 28, 1914.

Russia experienced the most casualties in World War I, with an estimated 1.7 million soldiers killed.

The Treaty of Versailles was the main peace treaty that ended World War I, signed on June 28, 1919.

The main goal of the Treaty of Versailles was to punish Germany for its role in World War I, by imposing harsh reparations and territorial losses.

Germany was the main aggressor in World War II, as it invaded and occupied numerous countries in Europe and Asia.

The invasion of Poland by Germany on September 1, 1939, is often considered the start of World War II.

The Soviet Union experienced the most casualties in World War II, with an estimated 27 million soldiers and civilians killed.

The Battle of Stalingrad, which lasted from July 1942 to February 1943, is often considered the turning point of World War II, as it marked the beginning of the end of German dominance on the Eastern Front.

The Treaty of Potsdam, signed on August 2, 1945, was the main peace treaty that ended World War II.

The main goal of the Treaty of Potsdam was to punish Germany for its role in World War II, by imposing harsh reparations and territorial losses.

The United Nations was created after World War II to promote peace and cooperation among nations.

The fall of the Berlin Wall on November 9, 1989, is often considered the end of the Cold War.