My take on war is that the winner is the one with the most sustained resources. The North had the industry and population to outlast the South. The Allies had the industry out of reach of the Germans and the Japanese plus a much larger population. This last component of resources was forgotten in Vietnam and in Palestine. The Vietnamese had many more people willing to die for their cause than the U.S. did, despite the latter's greater access to industry. The Israelis are aware that they are surrounded by a much larger population that does not share its interests; the more the Israelis make war, the more enemies they create.
You can find a much broader perspective on how war rarely accomplishes its ends in "War and Truth in Libya and Palestine", Tarak Barkawi, Al Jazeera English, 2011-04-28.