John Walter Ripley was born on June 29, 1939 in Radford, Virginia. He enlisted into the Marine Corps in 1957. A year later, he was appointed to the U.S. Naval Academy by the Secretary of the Navy. He graduated in 1962 with a Bachelor of Science degree in electrical engineering, and received his commission as a second lieutenant. After completing the Basic School, he joined the Marine Detachment on the USS Independence.

After his sea duty, he joined 2nd Battalion, 2nd Marines. In May 1965, Ripley was transferred to 2nd Force Reconnaissance Company, and after training, he deployed to Vietnam with his platoon.

In October 1966, Ripley joined 3rd Battalion, 3rd Marines in South Vietnam, I Corps. He served as Company Commander of Lima Company, known as "Ripley's Raiders," was wounded in action, then returned to active duty and completed his combat tour.

During his two years of Vietnam service, he participated in 26 major operations. In addition to numerous decorations for extensive combat experience at the rifle company and battalion levels, Ripley was awarded the Navy Cross for extraordinary heroism in destroying the Dong Ha bridge during the 1972 North Vietnamese Easter Offensive (also known as the Nguyen Hue Offensive). That action is memorialized at the Naval Academy with a large diorama titled "Ripley at the Bridge."

Ripley dangled for three hours under the bridge in order to attach 500 pounds of explosives to the span, ultimately destroying it. His action, conducted under enemy fire while going back and forth for materials, is thought to have thwarted an onslaught by 20,000 enemy troops and was the subject of a book, The Bridge at Dong Ha, by John Grider Miller.

Following his tours in Vietnam, Ripley served with Marine Force Reconnaissance, was an exchange officer with the British Royal Marines and was a Commanding Officer of 1st Battalion, 2nd Marines and the 2nd Marine Regiment. His final tours in the Marine Corps were in charge of the NROTC detachments at Oregon State University and the Virginia Military Institute, and as the senior Marine at the United States Naval Academy teaching English and history. He earned the "Quad Body" distinction for making it through four of the toughest military training programs in the world: the Army Rangers, Marine reconnaissance, Army Airborne and Britain's Royal Marines, according to Miller's book. He was also the only Marine officer to be inducted in the U.S. Army Ranger Hall of Fame. Ripley retired from the Marine Corps in 1992 after 35 years of active duty service.

Coloney Ripley died suddenly in his home in Annapolis, Maryland on October 28, 2008 at age 69. He was buried with full military honors on November 7 at the United States Naval Academy.

In addition to the Navy Cross, his personal decorations include the Silver Star, two Legions of Merit, two Bronze Star Medals with 'V' for Valor, the Purple Heart, the Defense Meritorious Service Medal, the Meritorious Service Medal, the Navy Commendation Medal, the Combat Action Ribbon, the South Vietnamese Army Distinguished Service Order, 2nd Class, and the South Vietnamese Cross of Gallantry with Gold Star.

In 2002, he also became the very first Marine officer to receive the "Distinguished Graduate Award", the highest and most prestigious award given by the United States Naval Academy. Also, in May 2004, Marines of the 22nd Marine Expeditionary Unit named a Forward Operating Base after him (FOB Ripley) in south-central Afghanistan.

In July 2006, the Naval Academy Prep School in Newport, Rhode Island dedicated its new dormitory as "Ripley Hall", honoring their former graduate. "Ripley Hall Dedication Ceremony / IMG_0627". US Naval Academy Alumni Association (2006-07-13). Retrieved on 2008-11-04.

On June 11, 2008, Ripley became the first Marine to be inducted into the U.S. Army Ranger Hall of Fame - honored for the assault on the Dong Ha Bridge, on Easter morning 1972.

On March 30, 1972, the Peoples’ Army of Vietnam — the North — abandoned irregular warfare, launching the biggest conventional offensive of the war. The “Easter Offensive” far exceeded the Tet Offensive of 1968 in scope. Hoping to negate U.S. air power by taking advantage of the monsoon season, they attacked with massive armor and artillery on three fronts, including the area south of the Demilitarized Zone (DMZ). On this northern front, one division attacked directly south across the DMZ toward Quang Tri while another assaulted eastward from Laos along Route 9, through Khe Sanh and into the Quang Tri River Valley.

Caught by surprise, the South Vietnamese could only try to slow the offensive, retreating south of the Cua Viet River at Dong Ha. But 20,000 soldiers and 200 tanks from the North were poised to strike across the river — and they were planning use a bridge defended by about 600 Southern soldiers, who had been ordered to “hold and die.” John related later that he would never forget that order. The only way to stop the North was to destroy the bridge. Fortunately, South Vietnamese engineers had placed 500 pounds of TNT and plastic explosives near the bridge. But the explosives would still need to be placed properly to bring down the twin spans.

Aided by a U.S. Army officer, Maj. James Smock, John set up the explosives. He had to expose himself to enemy fire while swinging hand over hand along the bridge’s girder, with heavy loads of explosives slung over his shoulders. The odds against success seemed insurmountable.

As John observed later, “the idea that I would be able to even finish the job before the enemy got me was ludicrous.” However, “when you know you're not going to make it, a wonderful thing happens: You stop being cluttered by the feeling that you're going to save your butt.” But John never lost his sense of humor. In his report, he observed:

[The enemy,] rather than concentrating their fire on me — and I certainly couldn’t have made it through had they done so — they seemed to be watching incredulously as my body would appear, then disappear, hanging above the river. The enemy watched with a mixture of what seemed to be humor and amazement. In my judgment, they knew their massive assault would be successful and whatever I happened to be doing was relatively inconsequential; besides, I was providing them amusement.

According to John Miller, the author of The Bridge at Dong Ha, which details the battle and John’s actions, “a lot of people think South Vietnam would have gone under in '72 had he not stopped them” by destroying the bridge.

No one has described John’s actions better than my friend, Gerry Turley, the senior Marine adviser during the Easter Offensive in his book of the same name. John’s actions constituted “an epic example of fortitude, extraordinary bravery and personal resolve to defeat the enemy by fulfilling the last order, even if it means losing [one’s own life].” For his actions at the Dong Ha Bridge, John was awarded the Navy Cross, the nation’s second-highest award for valor.