But the happy times couldn´t last for a very long time. After the period of growth soon begun the troubles. There were big differences between industrial North and agricultural South. The slavery was another big problem. The men from North wanted to se the blacks free. The southern states economy was based on slavery so they were against it. And the war begun. This war is known as Civil war, or the war the North against the South. This war begun in the year 1861 and lasted till 1865. But during the war (1863) the President Abraham Lincoln set the blacks free and they fought on the side of North. So the North won but a short time after, Abraham Lincoln was assassinated. In the beginning of the 20th century was a great depression all over the world and many people were seeking for job. That is why in these times there were big waves of immigrants in the States. Especially Slavonic people were coming as a cheap labor force. But in the year 1929 the great depression came in the US too. The immigrant wave was stopped because there was not enough work for American citizens. After this the life in America begun to be normal. Till the date of 7th December 1941. On this day the Americans were attacked in Pearl Harbor by the Japanese army. And it means the Americans started to fought in the World War II. With the help of British, French and Russian soldiers they won the war and their leader post in the world was established. This position was characterized by the iron curtain between the United States and Russia. After the World War II. several interested things happened which must be mentioned. 1950 – 1953 lasted the Korean war and 1961 – 1973. 22nd of November 1963 was assassinated John F. Kennedy and in the year 1969 Neil Armstrong as a first man stepped on the Moon. As we can see the history of the United States of America is short, maybe 500 years. But he other thing is, that in these years US started to exist, become independent, fought in several wars and become a world superpower. This republic was based on democracy and the same chances for everybody. The next thing I want to speak about is the civilization. We distinguish 3 types (waves) of civilization: A) agricultural civilization. In this civilization are important basic social values like cattle, forest or land. The land is the main factor. The importance of man is given by the land he owns. We can still see this civilization wave in some countries, US too.