My guess is 100 miles I hope that helps :)
London and Paris are major. rome? Athens?
Operation Barbarossa was the Nazi German military invasion of the "USSR", since this was the famous surprise attack by Germany that broke the Nazi-Soviet Pact in World War II.
Answer:
First though (not part of the anwser) you could put something like I think that Thoma Clarkson's motive to publishing this drawing was to show people in the future what the ship would have looked liked.
