What do Dresden, Hiroshima, and 9/11 share in common?

All of the above events share tragedy and loss; Dresden with its horrific battle, something Thomas experience first-hand, Hiroshima and the way the interview Oskar watches of the woman holding her dead child connects to his grandfather's search for Anna, and 9/11... the event that connects Oskar to the large-scale violence inflicted of all three events.