The number of refugees who have entered Europe this year has topped 1 million. The International Organization for Migration said the tally marks a fourfold increase over last year. It’s the greatest exodus of people since World War II. The vast majority have arrived by sea. Nearly 3,700 people have drowned or remain missing after attempted sea crossings. Most of the refugees are from Syria, Iraq and Afghanistan, countries ravaged by war. Click here to see our report on refugees of U.S. wars who are living in France’s largest refugee camp.