/kloc-In the middle of the 0/8th century, there was a rift between the British colonies in the United States and Britain. The expansion of the colonies made them consciously persecuted in Britain, and they had the idea of independence. 1774, representatives from 12 states gathered in Philadelphia to hold the so-called first continental congress, hoping to find a reasonable way to solve the problem peacefully with Britain. But the British king insisted that the colony must unconditionally submit to the British king and accept punishment. 1775, the war broke out in Massachusetts; In May, the second continental congress was held, which strengthened the determination of war and independence, issued the famous Declaration of Independence, and put forward sufficient reasons for fighting this war, which was also the factor of final victory. 178 1, the us military won a decisive victory; 1783, the United States and Britain signed the Treaty of Paris, ending the War of Independence.

Form a new government (1784- 18 19)

The success of the revolution gave the American people the opportunity to express their political ideas in the form of legislation. 1787, a federal conference was held in Philadelphia, during which Washington was promoted as the chairman. They adopted the principle that the power of the central government is universal, but it must be carefully defined and explained. At the same time, they also accepted the fact that the national government must have the right to tax, mint money, adjust commerce, declare war and conclude treaties. In addition, in order to prevent the central power from being too large, Montesquieu's political theory of balance of power is adopted, that is, three departments of equal cooperation and mutual checks and balances are set up in the government, that is, the legislative, administrative and judicial powers are reconciled and balanced with each other, and no power occupies a controlling position.

Westward expansion (1820- 1849)

/kloc-At the beginning of the 9th century, thousands of people crossed the Appalachian Mountains and moved westward. Some pioneers moved to the border of the United States and even went deep into the territory of Mexico and Oregon between Alaska and California. Pioneers bravely and diligently sought a better life in the west.

Civil war (1850- 1869)

The causes of civil war are not only economic, political and military issues, but also ideological conflicts. The civil war exposed America's weakness. The existence of this country has been tested. After this test, the United States embarked on the road of a centralized and modern country. There is a dispute between the north and the south on the issue of slavery. The main policy of the south in national politics is to protect and expand the interests represented by the "cotton and slavery" system; The northern States are mainly manufacturing, commercial and financial centers, and there is no need to rely on slaves for these production. This kind of economic and political conflict has a long history. In the early 1960s, 1 1 Southern states broke away from the federation and formed another government, while the North said that it would do whatever it took to achieve reunification. 186 1 year, the civil war broke out. Americans fought face to face for four years, and the south was severely damaged, leaving deep scars. 1865, the defeat of the north not only shows the reunification of the United States, but also shows that slavery is no longer practiced in the whole country.