World War I (1914-1918) was primarily caused by tensions between European powers due to military competition, nationalism, and entangled alliances. The effects included millions of casualties, economic distress, and the Treaty of Versailles, which imposed harsh penalties on Germany and fostered resentment that contributed to World War II. World War II (1939-1945) occurred primarily due to the rise of totalitarian regimes in Germany, Italy, and Japan, as well as unresolved grievances from WWI. The effects included even larger devastation, the Holocaust, the emergence of the United States and Soviet Union as superpowers, and the beginning of the Cold War.
Imagine you are an expert on the historical events of the 20th century. Compare and contrast the causes and effects of World War I and World War II.