Washington (CNN) -- More than 42 years after Air Force Chief Master Sgt. Richard L. Etchberger died on a Laotian mountaintop, President Barack Obama on Tuesday awarded him the Medal of Honor, saying, "It's never too late to do the right thing. It's never too late to pay tribute to our Vietnam veterans and their families." 

Etchenberg's three sons were at the White House for the ceremony. For decades they didn't know about their father's heroism. 

Cory Etchberger was in third grade in 1968, when he was told that his father had died in a helicopter accident in Southeast Asia. At age 29 he learned the truth, when the U.S. Air Force declassified his father's story. 

"I was stunned," he told CNN during a visit to his hometown of Hamburg, Pennsylvania. 

During the Vietnam War, U.S. troops weren't supposed to be in neutral Laos, so Richard Etchberger and a handful of colleagues shed their uniforms and posed as civilians to run a top secret radar installation high on a Laotian cliff. Called Lima Site 85, it guided U.S. bombers to sites in North Vietnam and parts of Laos under communist control. 

"Dick and his crew believed they could help turn the tide of the war, perhaps even end it," said Obama. 

The North Vietnamese wanted to eliminate the installation, and early on the morning of March 11, 1968, its soldiers succeeded in scaling the 3,000-foot precipice and launching an attack. 

Timothy Castle, of the CIA's Center for the Study of Intelligence, wrote the book "One Day Too Long: Top Secret Site 85 and the Bombing of North Vietnam." He calls Etchberger "a hero." 
Who was in third grade?
When was he in 3rd grade?
Who died?
What was his ranking?
Did he have children?
how many?
What was he being awarded?
Who was awarding him with it?
How did he die?
Was that actually how he died?
When did he learn the truth of his fathers death?
What was Richard's nickname?
Who wrote a book?
What was the book called?
Was Richard called a hero?
How did Richard exactly die?
What war did he die during?
Cory Etchberger
Cory Etchberger was in third grade
in 1968
Cory Etchberger was in third grade in 1968
Richard L. Etchberger
Richard L. Etchberger died on a Laotian mountaintop
Air Force Chief Master Sgt.
Air Force Chief Master Sgt. Richard L. Etchberger
yes
Etchenberg's three sons
three sons
Etchenberg's three sons
Medal of Honor
awarded him the Medal of Honor,
Barack Obama
President Barack Obama on Tuesday awarded him 
in a helicopter accident
his father had died in a helicopter accident
no
Cory Etchberger was in third grade in 1968, when he was told that his father had died in a helicopter accident in Southeast Asia. At age 29 he learned the truth, when the U.S. Air Force declassified his father's story. 
when he was 29
. At age 29 he learned the truth
Dick
Dick and his crew
Timothy Castle,
Timothy Castle, of the CIA's Center for the Study of Intelligence, wrote the book
"One Day Too Long: Top Secret Site 85 and the Bombing of North Vietnam."
wrote the book "One Day Too Long: Top Secret Site 85 and the Bombing of North Vietnam."
yes
He calls Etchberger "a hero."
no
its soldiers succeeded in scaling the 3,000-foot precipice and launching an attack. 

the Vietnam War
During the Vietnam War