That all stems from Nixon ordering Deputy Attorney General William Ruckelshaus to fire Special Prosecutor Archibald Cox; Ruckelshaus refused, and resigned. Nixon then ordered the third-most-senior official at the Justice Department, Solicitor General Robert Bork, to fire Cox. Bork carried out the dismissal as Nixon asked. Which also explains why Bork was, well Borked 14 years later at the confirmation process to become a Supreme Court Justice.
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Thank you