All five of these factors were influential in leading to the outbreak of war in 1939.
The Treaty of Versailles which was signed after the First World War left Germany feeling aggrieved and angry. The German people felt humiliated and wronged as the treaty had imposed new geographical boundaries on the country. Germany had lost to France the industrial region of Alsace Lorraine and this had an adverse effect on Germany's economy.
The economic depression which started in America with the Wall Street Crash in 1929 had a devastating effect on the economies of Western Europe, and particularly in Germany. Unemployment and poverty led to dissatisfaction with the government, and this in turn enabled Hitler to gain popularity and power.
Hitler's ideas of German superiority appealed to many German people as they came to believe that under Hitler Germany could become a great and powerful nation. He offered them something to believe in and he offered them a scapegoat, the Jews, whom they could blame for the troubles in their country. Hitler's actions, such as attacking Czechoslovakia, threatened peace in Europe.
Meanwhile, Japan was expanding its military and technical power, and was in a position to launch a disastrous attack on America.
However, the countries of America, France and especially Britain were determined to follow a policy of appeasement. After the First World War, the League of Nations had been set to deal with conflicts through diplomacy and peaceful means. Therefore, Hitler had an opportunity to expand his power before the Western countries finally realised that appeasement was not going to work.