Which event marked the beginning of direct combat involvement for U.S. Marines in the Vietnam War?

The landing in Da Nang in 1965 is recognized as the beginning of direct combat involvement for U.S. Marines in the Vietnam War. This event marked a significant escalation in the U.S. military presence in Vietnam, transitioning from advisory and support roles to direct engagement in combat operations. The arrival of approximately 3,500 Marines was intended to provide security for the American presence and support the struggling South Vietnamese government against the insurgency and North Vietnamese forces.

The Battle of Khe Sanh and the Fall of Hue City occurred later in the conflict and were pivotal battles but did not initiate U.S. direct involvement, rather they were part of the ongoing military engagement. Similarly, Operation Urgent Fury, which took place in Grenada in 1983, is unrelated to the Vietnam War and represents a different military operation entirely. Therefore, the landing in Da Nang stands as the key turning point that marked the U.S. Marines' direct combat role in Vietnam.