If you think today’s political rhetoric is overheated, imagine what goes on inside a vertebrate embryo. There, two armies whose agendas are poles apart, engage in a battle with consequences much more dire than whether the economy will recover — they are battling for whether you (or frogs or chickens) will have a forebrain. A new study reveals that a foot soldier of one army — the ventralizers — deploys a weapon that disarms the other — the dorsalizers — leaving the embryo free to develop a proper brain. Those findings define how the embryonic nervous system develops and could shed light on mechanisms underlying colon cancer.