 With the installation of the Thieu and Ky government (the Second Republic), the U.S. had a pliable, stable, and semi-legitimate government in Saigon with which to deal.With the advent of "Rolling Thunder", American airbases and facilities needed to be constructed and manned for the aerial effort.On March 8, 1965, 3,500 United States Marines came ashore at Da Nang as the first wave of U.S. combat troops into South Vietnam, adding to the 25,000 U.S. military advisers already in place.