This will give you peace of mind, in that you can verify whether or not a professor has submitted a letter. It also gives you a polite way to ask a follow-up: I see that you haven't checked off the spreadsheet for X and it's due in three days.
Of the nearly 200 countries out there, the Brits have invaded all but 22. That is just about 90% of all countries! Mongolia, the Ivory Coast, Bolivia and Sweden are among the selective group of making it to 2013 without a British invasion. Here is the map showing where (pink) the British have invaded.
When the Saxons and Angles invaded Britain they had to defeat the native Britons. This is the era of King Arthur who, legend states, defended Britain against the invaders. The Saxons managed to defeat the Britons and take control of the country.