I had an excellent suggestion from a reader - check the coins the Vikings had in their possession. Look for the dates on the coins. That's actually a pretty good idea. I did some research and learned that Ninth Century Vikings didn't use coins. It wasn't until a hundred years later before coins began to be produced in Norway. They used bullion before then, bulk gold or silver. (Grab a bunch of gold cups and plates from a church, that sort of thing.) However, it's still a good idea, because coins were available in England, so they would have been taken in any raids and the Vikings would understand them. I added a short paragraph about that. Thanks!
Chapter 8 looks at military medicine. Up until this point, what I knew about military medicine was based on MASH, a 1970s TV show about a 1950s war, where Hawkeye and BJ performed 'meatball surgery' in tents by the light of a kerosene lantern. Modern military field hospitals are vastly different. They are modular and palletized. When they are airlifted or driven to the site they are expanded and unfolded and then linked together in a variety of configurations by an engineer detachment. The engineers will probably take longer leveling the site than bolting the pieces together. If you need a dental office or an OB/GYN suite, just bring in the correct modules. And for those curious, yes, they have laparoscopic capabilities, which was the most astonishing thing I learned.