This book, Elizabeth the Great, is a biography of Queen Elizabeth I of England. Her reign spanned four decades, from 1558 to 1603. She is called Gloriana because her reign was time of properity and growth for England.
It could be that her death was natural causes, just old age. She was 70 years old when she died, which would have been a very long life for that era. Contemporary reports show, however, that after the death of Robert Devereux, Earl of Essex, to whom she was very attached, she began to decline. She seemed to be depressed, and records show that she refused to allow her doctors to examine her or to rest in bed, choosing instead to stand for hours. Eventually her ladies in waiting put cushions on the floor, and she lay there for four days. It is said that when her adviser Lord Cecil said, "Your Majesty, to content the people, you must go to bed," she answered with, "Little man, little man, the word must is not used to princes."
Finally, she became so weak that her attendants were able carry her to her bed without complaint. She died on March 24, 1603. She just stopped breathing. John Manningham reported that "Her Majesty departed this life, mildly like a lamb, easily like a ripe apple from the tree."
I don't think we'll ever know whether she had a disease or a form of cancer, or whether she just lost the will to live.