One of the most spectacular features of the tree every year is its nighttime glow. But in 1944, the Christmas trees (yes, three trees, in fact) remained unlit. The backstory is that two years earlier, Rockefeller Center unveiled three small trees dedicated to the U.S. effort in World War II each one either red, white or blue. The patriotic trees were replanted over the next couple of years, but in 1944, in line with wartime blackout regulations, the trees stayed dark. When the war ended in 1945, the organizers made up for lost time and used six ultraviolet-light projectors to make all 700 fluorescent globes on that year's tree appear to glow in the dark.