A British monarch had never set foot on American soil until the 1939 state dinner for King George VI. It was held at the height of concern over the belligerent actions taken by Nazi Germany in Europe, and President Franklin D. Roosevelt was well aware of the importance of the U.S.'s relationship with Britain. So, as you can imagine, the dinner was meticulously planned. In fact, Roosevelt was reportedly involved in even the most minute details of the visit. But it paid off. The dinner led to closer relations between the two democracies and eventually to one of the world's strongest diplomatic alliances, which endures to this day.