The history of the United States began with the meeting of the First Continental Congress in September 1774. The Revolutionary War ensued in which the United States won its freedom from England. England tried to seize its former colonies again, but the War of 1812 ended in a stalemate. The Louisiana Purchase added a significant amount of land to the United States. The United States launched a War against Mexico that further enlarged its territory with the addition of areas in the Southwest. However, a Civil War detracted from further progress in acquiring new territories. The United States became involved in World War I in its first global conflict. It then underwent a Great Depression, which the entrance into World War II made it regain its economic prosperity. Great strides were made in technology, including manned trips to the moon. Civil rights issues also became prominent with many significant events that resulted in new laws against discrimination. A major war was also fought in the gulf area to protect the oil interests of the world. The 21st century has been mainly one of dealing with terrorism and a Great Recession. Two major wars have depleted the resources of the country and have contributed towards the ever-escalating national debt, which now stands at 19.5 trillion dollars. In the 243 years of its existence since 1774, the United States has experienced the assassination of 4 Presidents, and the deaths of 4 other Presidents in office. In spite of this, the country has always found someone else to lead the way towards a brighter future. It has also withstood many events that have reverberated throughout the world, including the 9/11 terrorist acts by Al-Qaeda on American soil.