Fifty-five years ago today, on March 18th, 1970 (February 11th, 1970 in the lunar calendar), Cambodia's Lon Nol group launched a coup in Phnom Penh to overthrow the Sihanouk regime. On March 18, 1970, when Prince Sihanouk visited the Soviet Union, the right-wing Lon Nol group in Cambodia launched a coup with the planning and assistance of the United States to depose Sihanouk. The Lon Nol regime introduced the disaster of the U.S. military into the country. The day after the coup in Phnom Penh, Lon Nol approved the U.S. military to dispatch a huge fleet of B-52 aircraft to "carpet" bomb the "Ho Chi Minh Trail" in eastern Cambodia. U.S. military advisers were sent to the government forces in Phnom Penh. At the same time, in order to resist the United States and save the country, Prince Sihanouk cooperated with the Khmer Rouge. With the support of Prince Sihanouk and the Viet Cong, the Khmer Rouge became even more powerful. The base areas rapidly expanded and connected into one piece, and went deep into the jungle to launch guerrilla warfare, which played an important role in protecting the Ho Chi Minh Trail, the lifeline of the Vietnam War. In 1975, the Khmer Rouge defeated the Lon Nol regime in one fell swoop.