Complex sentence: Although Dulles'involvement in the Bay of Pigs endeavor gained him enough ill repute to be fired from the CIA during Kennedy's administration, he didn't let this stifle his ambition.
Split into simpler sentences: Although Dulles'involvement in the Bay of Pigs endeavor gained him enough ill repute to be fired from the CIA during Kennedy's administration. However, he didn't let this stifle his ambition.