<span>The United States had troops in Saudi Arabia</span>
Nationalism heightened in the 19th century and heading into the 20th century. The nationalistic fervor by people in Europe had them each viewing their own nations as better than the others, in competition with the others. This would lead to an increase in tension between the nations.
Imperialism expanded on that nationalistic rivalry by carrying their competition to other parts of the globe. The nations of Europe sought to grab control for themselves over parts of Asia and Africa. When war erupted, that also meant it would become a world war because the European nations would include people from their imperial territories in the war.
Militarism grew ever more potent as the 20th century opened. The competition between nations included a massive arms race in terms of expanding armies and navies. The nations also sided up in competing military alliances and made military battle plans as to how they might fight a war if war came. When a cause for war broke out, all those preparations propelled the nations of Europe into war recklessly.
Explanation: The meeting of the First Congress was important because the representatives from the nine colonies put aside their local differences and had joined together in a mutual cause. The delegates of the Stamp Act Congress drew up a "Declaration of the Rights and Grievances of the Colonists".
The name of the ruler of Russia before the revolution was Czar Nicholas II.