Portugal and Spain were at the head of the European sea exploration by the end of the 15th century, especially Portugal. The Portuguese had been navigating around Africa for many decades and in the final years of the century, the Portuguese circumnavigated Africa and made it to Asia. Columbus had arrived in the New World in 1492 and Spain wanted to explore the new routes to look for gold and riches. There was a dispute over the right to explore and conquer, and the crowns of both countries appealed to pope Alexander VI, who drew a line in the middle of the Atlantic and gave Spain all the territories to be discovered west of the line, and gave Portugal all the territories found east of the line.
The main reason why German <span>u boats sank unarmed ships such as the lusitania is because the Germanys believed that many such boats were carrying supplies that were helping their enemies. </span>
The reason that the wartime alliance between the United States and the Soviet Union unraveled is because the United States was against communism but the Stalin wasn't. All of the land occupied by the Soviet Red Army were controlled by communism and Stalin wanted to spread this into Western Europe and West Berlin.
