Queen Elizabeth II

Born on April 21, 1926, Elizabeth Alexandra Mary became queen of England on Feb. 6, 1952, upon the death of her father, George VI. She is the third-longest-reigning monarch in the history of Britain. She endeared herself to the British public as princess during World War II, when she rolled up her sleeves and joined the war effort in the Women's Auxiliary Territorial Service. As soon as her father's health declined in 1951, Elizabeth began picking up many of his duties as the heiress apparent. Her reign has been marked by milestones -- like being the first British monarch to address a joint session of the U.S. Congress -- and public turmoil, such as the divorce of her son Charles from Princess Diana. Here is a collection of photos of England's third-longest serving monarch.