On March 8, 1965, the first US combat forces arrived in Vietnam on the beaches at Da Nang. My uncle, John J Reynolds, was there with the 9th Marines. From the article:
"U.S. Marines land at Da Nang
The USS Henrico, Union, and Vancouver, carrying the 9th Marine Expeditionary Brigade under Brig. Gen. Frederick J. Karch, take up stations 4,000 yards off Red Beach Two, north of Da Nang.
First ashore was the Battalion Landing Team 3/9, which arrived on the beach at 8:15 a.m. Wearing full battle gear and carrying M-14s, the Marines were met by sightseers, South Vietnamese officers, Vietnamese girls with leis, and four American soldiers with a large sign stating: “Welcome, Gallant Marines.” Gen. William Westmoreland, senior U.S. military commander in Saigon, was reportedly “appalled” at the spectacle because he had hoped that the Marines could land without any fanfare. Within two hours, Battalion Landing Team 1/3 began landing at Da Nang air base.
The 3,500 Marines were deployed to secure the U.S. airbase, freeing South Vietnamese troops up for combat. On March 1, Ambassador Maxwell Taylor had informed South Vietnamese Premier Phan Huy Quat that the United States was preparing to send the Marines to Vietnam. Three days later, a formal request was submitted by the U.S. Embassy, asking the South Vietnamese government to “invite” the United States to send the Marines. Premier Quat, a mere figurehead, had to obtain approval from the real power, Gen. Nguyen Van Thieu, chief of the Armed Forces Council. Thieu approved, but, like Westmoreland, asked that the Marines be “brought ashore in the most inconspicuous way feasible.” These wishes were ignored and the Marines were given a hearty, conspicuous welcome when they arrived."