Britain's King Charles heads to the United States next week for the most high-profile trip of his reign so far, on a mission to shore up the future of the two allies' "special relationship" which the Iran war has plunged to its lowest point in 70 years. The state visit marks the 250th anniversary of the U.S. declaration of independence from British rule, when the then 13 American colonies decided to split from King George III, Charles's five-times-great-grandfather. For Charles, it will be a moment to reflect on how Britain and the United States have come together since then to...