A gun salute, trooping the color, and lighting of the beacons marked the beginning of four days of celebrations honoring Queen Elizabeth II's 70 years on the throne on June 2 and displaying British military traditions stretching from the days of horse and cannon to the jet age. The celebrations got underway with trooping the color, an annual military review commemorating the sovereign's official birthday since 1760. However, the queen will not attend a thanksgiving church service on June 3 after experiencing "some discomfort" at events on June 2, Buckingham Palace announced. The celebrations are taking place over a four-day holiday weekend.