Beckwith lettered in football for the Bulldogs, and was approached by the Green Bay Packers for the 1950–51 NFL draft, but turned it down in favor of a military career.

Special Forces at the time focused on unconventional warfare, and especially foreign internal defense: i.e. training indigenous personnel in resistance activities.

In 1965, Beckwith volunteered to return to Vietnam where he was selected to command a high-priority special forces unit Project Delta (Operational Detachment B-52).

[1] Following his promotion to Major, Beckwith led B-52 in the rescue of the besieged Special Forces camp at the Siege of Plei Me,[1] during which President Lyndon B. Johnson requested to speak to him directly over radio in order to congratulate and encourage him; his iron-fist disciplinarian style of running of the camp is described in detail in CBS News Journalist John Laurence's book "The Cat from Hué".

Beckwith transformed this phase from a scripted exercise based upon the Army's World War II experience, into a Vietnam-oriented jungle training regimen.

[1] The toughest job the battalion had was clearing a seven kilometer stretch along Route 547, running west of Huế, eventually defeating the determined NVA defenders so that Fire Support Base Bastogne could be established.

From 1973 to 1974, Beckwith served as commander, Control Team "B" with the Joint Casualty Resolution Center (JCRC) located at RTAFB Nakhon Phanom, Thailand.

[1] Under the Command of BG Robert C. Kingston, USA, JCRC's sole mission was to assist the Secretaries of the Armed Services to resolve the fate of servicemen still missing and unaccounted for as a result of the hostilities throughout Indochina.

The 5th Special Forces Group quickly formed the counter-terrorism unit Blue Light to fill in until Delta was fully operational.

[7] Beckwith led Delta Force's first mission, Operation Eagle Claw, the assault on the captured American embassy in Tehran, Iran early in 1980.

His granddaughter, United States Air Force Technical Sergeant Mary Howe (now Daniell), is an aerial gunner of 4th Special Operations Squadron and the daughter of Paul R.