WATCH: Retro 1974 Colbert covers the Watergate scandal with help from Pat Buchanan

On last night's episode of The Colbert Report, Stephen Colbert stepped back in time and covered the end of Richard Nixon's career as if the show were being taped in 1974.

His first guest was former Nixon speechwriter Pat Buchanan, for whom the 40th anniversary of Watergate has served as a way for the disgraced former MSNBC host to get back on television.

A smoking, side-burned Colbert began by asking Buchanan whether "the Nixon you knew was a tragic figure."

"Yes," Buchanan replied. "He was. Nixon had some flaws, and with the presidency of the United States, the flaws are magnified -- as they are in many tragedies, Shakespearean and Greek. And he was indecisive in Watergate, and he was too loyal to his friends, and he didn't act -- and if he had, I think he would have gone down in history as one of the great presidents, if you take a look at what he accomplished in his first term."

"He had detente with the Soviet Union," Buchanan continued, "arms control, opened up China, saved Israel in the Yom Kippur War, brought the troops home from Vietnam, brought all the POWs home. He was an extraordinary success, but Watergate erased it all."

"Now," Colbert interrupted, "forty years ago today, the so-called 'smoking gun' tape was released. Tell the people what it was."

"The 'smoking gun' tape was the tape with June 23, 1972 in which Nixon was talking about containing the investigate into Watergate. Nixon had [told the American people] that he had not seen the tapes, that he didn't know there was a cover-up."

"And the tapes said," Colbert interjected, "that Nixon knew there was a cover-up and he was encouraging the cover-up. Should he have destroyed the tapes?"

"Certainly," Buchanan responded. "He should never had made the tapes."

"But that's different," Colbert said. "That's like saying, 'Should you have destroyed the murder weapon?' Well, better not to murder someone. Did you advise him to destroy the tapes."

"Yes, I did," Buchanan said.

"I agree with you," Colbert replied. "Because if you're going to obstruct justice, go all the way."

"No," Buchanan said. "What he should have done is kept the tapes the Brezhnev all these foreign policy things, and also of John Dean, and take the rest of them and get rid of them."

"Because it turned out," Colbert said, "they had nothing else important -- no other evidence of his obstruction of justice."

"What he should have said after burning them," an irate Buchanan replied, "is impeach and be damned."

Watch the August 5, 2014 retro-episode of The Colbert Report below via Hulu.