They are the first in and last out. Marines are the guys who get called when shit needs to get done. Marines don't play around. Marines will fight you, fuck you, or run you a foot race... doesn't make a shit to them. Marines know of only one direction and it is forward. Marines are the fireman of the world, they go in when everyone else is running out.
Marines are at the business end when the world dials 911.
Marine A: We were taking fire for 16 hours, had 10 casualities, ran out of ammo and fought hand to hand with bayonets for three hours. We are Marines!!
Marine B: That's it? What the fuck did you do for the other 8 hours?
Marine A: Good Point!