The book is going to be a good resource. it is good to have people who knows combat lifesaver skills, BTLS, or even ATLS when there is potential someone is going to get hurt. i still keep a trauma bag in the house.

However, in an urban situation with multiple casualties, the best medical tool is still a functioning cell phone and calling 911. How common is it to see local "gansters" getting shot with 9 mms seeing the trauma bay, getting surgery, recovering, and going back to his old profession only to return to the trauma bay a year later... much more common than I thought. I have met bangers who have been dead multiple times if not for someone calling 911, having good paramedics take care of them in the field, and being close to the nearest ER.

in the country, you better hope there is a good helo landing strip nearby. a medevac will be your best survival tool to make it through the golden hour.