An example of self-sacrifice in Book the Second is Dr. Manette’s return to shoe-making when he realizes his daughter is about to marry into the family that imprisoned him.
Dr. Manette kept himself from going mad during his time in prison by making shoes. Once recalled to life, he kept his shoe-making equipment, unable to give it up. When he discovered that his daughter was about to marry the new Marquis St. Evremonde—the family that caused him to be locked up—he withdrew into himself.
Miss Pross, with a terrified face, was at his ear. “Oh‚ me, Oh me! All is lost!” cried she, wringing her hands. “What is to be told to Ladybird? He doesn’t know me, and is making shoes!” (Book 2, ch 18, p. 126)
Darnay (his real name is St. Evremonde) had no idea what effect his news would have on Dr. Manette. He wanted the father of his love to know the truth about him. He did not want to keep the secret from the family any longer. Darnay himself was a good man. He renounced his title, and did not want to be the Marquis St. Evremonde. Unfortunately, to Dr. Manetter the name came as a quite a blow.
The shoe-making is a self-sacrifice because Dr. Manette lets Darnay marry Lucie. He basically chooses to retreat into his psyche rather than stop the marriage. He does not prevent his daughter from marrying Charles, and he does not even tell her what is going on. The shoe-making is short-lived, fortunately, and the “Darnays” come back from the honeymoon none the wiser.
Dr. Manette’s not-entirely-voluntary self-sacrifice foreshadows Sydney Carton’s completely voluntary one. In each case, the man sacrifices himself so that Lucie can be happy.