O.E. dic "ditch, dike," a variant of dike (q.v.). Last ditch (1715) refers to the last line of military defenses.
edit: OK now I understand that your answer was for VG, not me.
My answer was for you, and that's why I quoted you.
Good night to you too.
Edited by Abramelin, 01 December 2012 - 10:58 PM.