Bruno is a 9-year-old boy growing up during World War II in Berlin. He lives with his parents, his 12-year-old sister Gretel and maids, one of whom is called Maria. After a visit by Adolf Hitler, Bruno's father is promoted to Commandant, and the family has to move to "Out-With" because of the orders of "The Fury" (Bruno's naïve interpretation of the word "Führer"). Bruno is initially upset about moving to Out-With (in actuality, Auschwitz) and leaving his friends, Daniel, Karl and Martin. From the house at Out-With, Bruno sees a camp in which the prisoners wear striped pyjamas. One day, Bruno decides to explore the strange wire fence. As he walks along the fence, he meets a Jewish boy named Shmuel, who he learns shares his birthday. Shmuel says that his father, grandfather, and brother are with him on this side of the fence, but he is separated from his mother. Bruno and Shmuel talk and become very good friends, although Bruno still does not understand very much about Shmuel and his side of the fence. Nearly every day, unless it's raining, Bruno goes to see Shmuel and sneaks him food. As the meetings go on, and Shmuel gets more and more skinny, Bruno's naïveté is proved, as he never realizes he is living beside a concentration camp.

When did the boy in the striped pajamas take place? Okie... think carefully first, then make a decision:
The relevant information to answer the above question is: Bruno is a 9-year-old boy growing up during World War II in Berlin. So, the answer is World War II.