The Nazis discovered it. The Allies won the war with it. It conquered diseases, changed laws, and single-handedly launched the era of antibiotics. Sulfa saved millions of lives—among them those of Winston Churchill and Franklin Delano Roosevelt Jr.—but its real effects are even more far reaching. Sulfa changed the way new drugs were developed, approved, and sold; transformed the way doctors treated patients; and ushered in the era of modern medicine. The very concept that chemicals created in a lab could cure disease revolutionized medicine, taking it from the treatment of symptoms and discomfort to the eradication of the root cause of illness.