What Was Pearl Harbor?By: Patricia Brennan Demuth, Who HQ Illustrator: John Mantha Series: What Was? A terrifying attack! On December 7, 1941, Japanese war planes appeared out of nowhere to bomb the American base at Pearl Harbor in Hawaii. It was a highly secretive and devastating attack: four battleships sunk, more than two thousand servicemen died, and the United States was propelled into World War II. In a compelling, easy to read narrative, children will learn all