Well, if you go by the WWII timeline anyway.
We went to war with Germany the day after Pearl Harbor (December 7, 1941--September 7 if you're George H W Bush*). Germany surrendered in May 1945, roughly 3 years 6 months later. We invaded Iraq roughly 3 years 3 months ago, so convoluted logic (the same that got us into Iraq in the first place) says we will prevail and emerge victorious in Iraq in 3 months!
Compare our situation in Iraq today with what was going on in Europe at roughly the same time in the war. Here are some events from January to March, 1945 (with February being roughly 3 years 3 months):
Jan 1-17 - Germans withdraw from the Ardennes.
Jan 16, 1945 - U.S. 1st and 3rd Armies link up after a month long separation during the Battle of the Bulge.
Jan 17, 1945 - Soviet troops capture Warsaw.
Jan 26, 1945 - Soviet troops liberate Auschwitz.
Feb 4-11 - Roosevelt, Churchill, Stalin meet at Yalta.
Feb 13/14 - Dresden is destroyed by a firestorm after Allied bombing raids.
March 6, 1945 - Last German offensive of the war begins to defend oil fields in Hungary.
March 7, 1945 - Allies take Cologne and establish a bridge across the Rhine at Remagen.
March 30, 1945 - Soviet troops capture Danzig.
http://www.historyplace.com/worldwar2/timeline/ww2time.htm#1945Now, now, or course some will say this is like comparing apples to oranges, but consider that the United States along with its allies pushed back and destroyed the Nazi War Machine and its allies in just 3 years 6 months. It's amazing what a country can do with a real reason to go to war; a just cause for going to war; competent leadership--both civilian and military (FDR, Truman, Eisenhower, Patton, Halsey, my dad...); an corporate/industrial base willing to take up the cause (Detroit goes from making Buicks to making tanks overnight); and a nation of citizens bonded together, willing to sacrifice for the troops ("Meatless Tuesdays," gas rationing, etc...). Considering we're fighting a ragtag, motely crew of "terrorists, no wait, "Saddam sympathizers," no, correction, "Insurgents" or whatever their name is this week, this "war" should be a real, well, "cakewalk."
So you see, folks, to quote Winston Churchill,
This is not the end. It is not even the beginning of the end. But it is, perhaps, the end of the beginning. (Speech given at the Lord Mayor's Luncheon, Mansion House, London, November 10, 1942), although, more optimistically than Churchill, we could very well say we're at "the beginning of the end."
Buck up! It's almost over...
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*7 Sep 1988 George Bush: "Today, you remember -- I wonder how many Americans remember -- today is Pearl Harbor Day. Forty-seven years ago to this very day we were hit and hit hard at Pearl Harbor." Attribution