As the nation was lost in the chaos and acrimony of civil war, President Abraham Lincoln and his family were suffering personal tragedies at home. And though President Lincoln is often depicted as a depressed figure-there was one constant source of joy, laughter, and even wisdom in his life: his youngest son, Tad Lincoln. This is the largely forgotten turnabout tale of how a son’s love not only changed his father’s life–but that of the entire nation–and forged a national holiday tradition.