A successful withdrawal is one of the most difficult things to pull off, militarily speaking. You have to provide covering fire, protection, for those withdrawing. Something like: 1,2,3,4,5,6 are going to withdraw. 2,4,6 provide protection for 1,3,5, who in turn provide protection for 2,4,6 to withdraw -- or in variations of this. In a situation like Iraq is and Vietnam was, you really shouldn't abandon your friends either.

If in the above example 1,2,3,4,5,6 all withdraw at once most will become casualties.

And of course the situation on the ground -- the tactical situation -- varies from moment to moment.

Getting into The Big Muddy is easy, getting out again is another story.