**Title: Official Beginnings of U.S. Military Involvement in the Vietnam War**

### Introduction
The Vietnam War, also known in Vietnam as the Resistance War Against America, was a prolonged conflict that took place from the late 1950s until 1975. The war pitted the communist government of North Vietnam and its allies in South Vietnam, known as the Viet Cong, against South Vietnam and its principal ally, the United States. The official start of U.S. military involvement in the conflict is subject to different interpretations, reflecting varying perspectives on when significant military operations began.

### Historical Context
After the end of French colonial rule in 1954, Vietnam was temporarily divided into North and South Vietnam. The division was intended to be temporary, with national elections scheduled for 1956 to unify the country. However, these elections were never held, leading to escalating tensions and conflicts between the communist North, led by Ho Chi Minh, and the anti-communist South, supported by the United States.

### Answer A: Military Involvement Beginning in 1965

#### The Gulf of Tonkin Incident and Resolution
The direct engagement of U.S. military combat units is often marked by the Gulf of Tonkin Incident in August 1964, in which U.S. warships reported being attacked by North Vietnamese forces. This led to the Gulf of Tonkin Resolution, passed by the U.S. Congress, which granted President Lyndon B. Johnson the authority to assist any Southeast Asian country whose government was considered to be jeopardized by communist aggression. The resolution served as the legal justification for the direct involvement of U.S. military forces.

#### Deployment of Combat Units
In March 1965, the U.S. began Operation Rolling Thunder, a sustained bombing campaign against North Vietnam, and the first U.S. combat troops were deployed. On March 8, 1965, 3,500 U.S. Marines landed at Da Nang, marking the first arrival of American combat troops in Vietnam. These developments in 1965 signify the scale-up of direct military involvement, hence marking this year as the commencement of formal U.S. combat operations in Vietnam.

### Answer B: First Arrival in February 1965

#### Early Military Assistance
Before 1965, U.S. involvement primarily consisted of military advisors and financial support to the South Vietnamese government. The official narrative often excludes these earlier contributions from the definition of "military involvement."

#### Arrival of Combat Units
Details from military records and veteran accounts indicate that smaller units and specialized groups had arrived earlier than the widely recognized March deployment. Specifically, in February 1965, the U.S. sent its first limited combat troops covertly to support South Vietnam, indicating broader involvement earlier than the large-scale troop deployment in March. This includes intelligence and logistical support units that played crucial roles in preparing for larger-scale military operations.

### Conclusion
The exact date marking the beginning of U.S. military involvement in Vietnam might differ based on sources and definitions of "military involvement." While some cite the widespread deployment of combat troops and public acknowledgment in March 1965 as the official start, others note smaller-scale troop arrivals and operations in February of the same year as evidence of earlier engagement. Both perspectives underscore the complexity of military and political escalation leading to full-scale U.S. involvement in the Vietnam War. This inquiry into the start dates not only sheds light on the military actions but also on how they are interpreted and remembered in historical narratives.