British Prime Minister Winston Churchill, one of the great leaders of World War II, often referred to his bouts of intense, prolonged depression as his “black dog.” When not battling depression, he had incredible energy and was highly productive. Churchill’s doctor, Lord Moran, wrote in his memoir “Winston Churchill: The Struggle for Survival” that he had diagnosed the prime minister with bipolar disorder. Despite his battles, or perhaps because of it, Churchill was a man of immense accomplishments.