On a road in Gaza City’s Zeitoun district, Palestinian resident Assem Dawla loaded mattresses and bags onto a truck as concrete yellow blocks marking the edge of Israel’s expanding military zone stood amid the rubble nearby. He said it was the seventh or eighth time since the war began that he and his family had been forced to leave a shelter because of Israeli evacuation orders and the advance of what residents call the yellow line. Zeitoun is one of at least five locations across Gaza where...