Oskar considers himself to have two "presumptive fathers"—his mother's husband Alfred Matzerath, a member of the Nazi Party, and her cousin and lover Jan Bronski, a Danzig Pole who is executed for defending the Polish Post Office in Danzig during the German invasion of Poland. Oskar's mother having died, Alfred marries Maria, a woman who is secretly Oskar's first mistress. After marrying Alfred, Maria gives birth to Kurt, whom Oskar thereafter refers to as his son. But Oskar is disappointed to find that the baby persists in growing up, and will not join him in ceasing to grow at the age of three.