There is one unlockable medal on the Pearl Harbor mission. When you are running to your PT boat, pick up a wounded sailor and carry him to either the nurse or navy docter. do this 3x and get the medal. If you cant find enough sailors, just wait until some get shot by Zeros.in boot camp, you can recieve medals depending on your shooting accuracy, theres a 50%,75%,and 100% medal. If you get 100%, you will get all 3.