vice admiral joe mcguire was head of s.e.a.l. training at time. >> you would have to go back to world war ii to have had one day where we experienced that many casualties at one time. >> mcguire says the entire s.e.a.l. community was devastated. it's a community marcus latrell and his twin brother decided they wanted to be part of when they were still teenagers. >> he had it in his head this is what we're going to do. it's going to be great, man. we can jump out of airplanes, shoot guns and blow stuff up. we get to scuba dive and there's an 80% chance we're going to die. i was like sign me up, man. >> marcus latrell became an s.e.a.l. at the age of 25 and says receiving the special force insignia was the proudest accomplishment of his life. >> do you remember when you got the tri dent put on yourselves? >> february 2nd, 2001. >> you remember the date. >> like it was my birthday. >> out of 86 people who started out in his s.e.a.l. training class, only 20 graduated. that's that sort of rigorous training that vice admiral mcguire sa

joe mcguire was head of seal training at the time. >> you would have to go back to world war ii to have had one day where we experience that many casualties at one time. >> reporter: mcguire says the entire seal community was devastated. it's a commune day marcus latrel and his twin brother decided they wanted to be part of when they were teenagers. >> he had in his head, this is what we'll do. it will be great. jump out of airplanes, shoot guns, blow stuff up, scuba dive and there is an 80% chance we're going to die. i'm like sign me up, man. >> reporter: he became a seal at the age of 25 and says receiving the special warfare insignia was the proudest accomplishment. >> do you remember getting the try dant put on your chest? . january 22nd, 2001. >> you remember the date? >> like my birthday. >> reporter: out of 86 people that started out, only 20 graduated. it's that sort of rigorous training that vice admiral mcguire says prepares seals for the fire fight marcus found himself fighting in the mountains of afghanistan. >> these are unremarkable men who do remarkable things. it's a war