I'm proceeding through the book very slowly. It is somewhat boring in these early stages. Now I don't know how accurate it is but from what I'm understanding, the Army got all the draftees. The Navy and Marines all got volunteers, those who didn't want to go to the army or go through the draft. Their rejection rates were however very similar to the Army's.
During the lead up to the war, and this is where I am now in the book, the Army had rejection standards which were quite strict. If you didn't meet the standards, you were rejected. But as time went on and they needed more men faster, they decided that some things which could be corrected to meet standards would be accepted. These included missing teeth and poor eyesight. So, they would take these individuals now, give them glasses and dentures.
I actually had to put the book down the first time I started reading it. I had a PTSD moment and came close to passing out. This leads me to believe that the book will get much better after I get through the boring introduction to military medicine. Very descriptive account of a bullet wound to the stomach which led to massive internal bleeding, blood spurting everywhere and removing the clotted blood from the abdomen by hand. 3 1/2-gallon transfusion. My surgeon told me I more or less burst when he cut into me, my chest was full of clotted blood, and they transfused 5 1/2 gallons to me. It was a bit much while eating lunch. Over it now.