E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
To give a person his congé is to dismiss him from your service. To take ones congé is to give notice to friends of your departure. This is done by leaving a card at the friends house with the letters P.P.C. (pour prendre congé) inscribed on the left-hand corner. (French, donner congé and donner à son congé.)