The darkest moment for American police this year was July 7 in downtown Dallas, when police officers providing security for a peaceful protest march suddenly found themselves under attack. And those weren't the only cops targeted this year. Deadly ambushes followed in Baton Rouge, Des Moines and Palm Springs.
As a result, many police will remember 2016 as a grim chapter in what many call the "war on cops." These ambush-killings of officers created a sense that they were under siege, threatening to poison the post-Ferguson debate over police reform.