The address is a central event of the state visit — the most high-profile of Charles' reign — and will be followed by a state dinner at the White House. WASHINGTON, April 28 (Reuters) - Britain’s King Charles will press the importance of unity with the United States and the need to defend democratic values in an address to Congress on Tuesday at a time of deep divisions between the two countries over the war in Iran. Charles and Queen Camilla are on a four-day state visit to the U.S. designed