When Robert Swan Mueller III deployed to Vietnam as a Marine infantry platoon commander in 1968, he surely knew it would be difficult. Mueller’s regiment, the 4th Marines, had faced bloody jungle warfare for months, and Mueller joined in them in a hellscape at the tail end of what military historians say was the service’s defining year in the war due to the size and scope of their operations.
Mueller ultimately earned two awards for valor, suffered a gunshot wound to his leg while responding to the ambush of fellow Marines and was reassigned after his injuries to serve as an aide-de-camp to the commander of the 3rd Marine Division, then-Maj. Gen. William K. Jones. In that role, Mueller excelled using a “diplomatic and congenial manner” that “significantly contributed to the rapport” Jones had with local Vietnamese officials and military officers, according to one account of Mueller’s actions.
These are among the details of Mueller’s military service outlined in documents released to The Washington Post by the National Archives. They were requested in the process of reporting a new article that details the rise of both Mueller, a former FBI director, and President Trump from similar wealthy circumstances to where they are now, as Mueller investigates potential links between Trump’s 2016 president campaign and the Russian government.
Mueller’s active-duty military service, often mentioned glancingly in profiles about him, began in August 1967, when he began training at the Marine Corps Officer Candidates School at Quantico, Va. Marine Corps documents show him in the service’s system dating back to August 1966, when he joined as an enlisted private, just weeks after graduating from Princeton University.

An excerpt of Robert S. Mueller III’s military records obtained by The Washington Post.
Mueller also attended the Army’s Ranger School, a highly regarded course for combat leadership, and its Airborne School. The assignments are unusual for Marines and, typically, set aside for just a handful of the best each year.
In combat, Mueller was a member of H Company, 2nd Battalion, 4th Marines, an infantry unit assigned along dangerous Mutter’s Ridge. It was a section of Quang Tri province that overlooked the Vietnamese Demilitarized Zone that separated North Vietnam and South Vietnam.
Mueller’s unit was decorated for two battles outlined in media accounts, including The Post’s today.
In the first, he led Marines through an eight-hour battle near Mutter’s Ridge in which the his men faced fire from small arms and automatic weapons, as well as a grenade launcher. Mueller, then a second lieutenant, moved among Marine positions in the battle, directing counter-fire and setting up a defensive perimeter and then supervising the evacuation of wounded Marines, including one who died.
For his actions, Mueller would receive the Bronze Star with “V” device and this citation:

An award citation detailing then 2nd Lt. Robert S. Mueller III’s valor in Vietnam in December 1968.
Four months later, Mueller was shot in the thigh responding to the ambush of some of the Marines under his command. A description of his actions from the Navy Commendation Medal with “V” that he received:

A Navy Commendation Medal with “V” citation describes Robert S. Mueller III’s actions the day he was wounded in Vietnam.
Despite his wounds, Mueller did not return to the United States. He healed nearby and then became an aide to a senior officer, Jones, who was a towering figure in the Marines. Jones had earned a Silver Star and Navy Cross for valor as a battalion commander during the World War II battles of Tarawa and Saipan, respectively, and went on to become a regimental commander in the Korean War.
Jones regarded Mueller well, said retired Marine Gen. James L. Jones, who was William Jones’s nephew. The younger Jones did not know Mueller during the Vietnam War, but he learned about Mueller’s past service to the elder Jones in former president Barack Obama’s White House, where Mueller was the FBI director and the younger Jones was his first national security adviser.
“He was always well prepared,” the retired general said of their shared time in the White House. “He’d done his research, he’d done his homework, and he presented his viewpoints in very clear, unambiguous terms. It was very easy to see where he came from.”
After Mueller returned from Vietnam, he served briefly in a headquarters unit at Henderson Hall, a Marine Corps installation near the Pentagon. He left active-duty service in August 1970. His last rank was captain.
In 2004, the Army’s Ranger Hall of Fame inducted Mueller. The shrine recognizes Rangers who have distinguished themselves among their peers, as well as Ranger School alumni like Mueller who did not serve in a Ranger unit, but graduated from Ranger School and distinguished  themselves in other ways. Voting for the board includes senior soldiers from the elite 75thRanger Regiment, leaders from the Army’s Ranger Training Brigade, and representatives from nonprofit organizations associated with the Rangers.
The hall credited Mueller with leading the FBI “through the dramatic transformation required in the aftermath of the September 11th terrorist attacks.” It cited his continued leadership in transforming the bureau into a modern counterterrorism agency.
“His law enforcement acumen, coupled with his valiant efforts to protect our homeland, will ensure his legacy of fearlessly leading the way,” the shrine’s leadership said, riffing on the Ranger motto: “Rangers Lead the Way!”