At around noon on May 2, 1972, two SR-71 Blackbirds dropped to 75,000 feet and flew separate Mach 2.5 passes over Hanoi, delivering two sonic booms within 15 seconds of each other. Their mission was vital and their timing critical. A third SR-71 had orbited offshore as a spare in case something forced one of the others to abort. The planes’ pilots and crew didn’t know the mission’s purpose, but executed it perfectly. The mission was repeated two days later.
The SR-71s had flown through the world’s most densely defended air space to deliver a message from America’s National Command Authority to a group of U.S. prisoners-of-war (POWs) held inside North Vietnam’s Hoa Lo Prison, better known as the “Hanoi Hilton.” The message consisted of two dots for the letter “I” in Morse code, telling them to “initiate” their escape plan. Thus began the final stages of Operations Diamond and Thunderhead, the Vietnam War’s last POW escape and rescue plan.
The United States had attempted POW rescues before, with the Son Tay Raid of Nov. 21, 1970, being the best known. But Operation Thunderhead was different. This time the plan originated within the POW camp itself. The primary authors of the plan were Captains John Dramesi and George C. McKnight of the U.S. Air Force and then-Lt. j.g. George T. Coker of the U.S. Navy. The men called their escape plan Operation Diamond.
All three had attempted to escape before, only to be recaptured within 36 hours. Coker and McKnight had escaped from a POW compound northwest of Hanoi in 1967, while Dramesi had made two previous attempts, the second one from the Hanoi Hilton. He had been moved there following his first escape attempt from a camp farther up the Red River. The men suffered weeks of torture as punishment for their actions. In fact, Dramesi’s partner in his second breakout, USAF Capt. Edwin L. Atterberry, died on May 18, 1969, ostensibly from an infection while under torture just eight days after their recapture.
Undaunted, Dramesi refused to give up on escape. One challenge he faced was opposition fromThe POWs would not betray Dramesi but a standing order from the Senior Ranking Officer (SRO) in the Hilton’s “Unity” compound, Lt. Col. Robinson “Robbie” Risner of the U.S. Air Force, required that no escape would be attempted without outside assistance. However, Risner approved the formation of a six-man escape planning committee led by Lt. Col. Hervey Stockman. Coker, Dramesi, and McKnight were joined by Maj. James H. Kasler and Capt. “Bud” Day, both USAF.
