On June 6, 1944, Allied forces stormed the beaches of Normandy in France on what became known as D-Day. The battle actually lasted more than a month but represented the turning point on the European front in WWII. Great Britain, the U.S. and Canada endured the heaviest casualties in the battle, respectively. The United States lost 1,465 soldiers in the Invasion of Normandy.
To put the matter into perspective, the United States did not lose its 1,465th soldier in Iraq until November 2004. (http://www.globalsecurity.org/military/ops/iraq_casualties.htm) In another words, it took 20 months for the United States to lose the same number of troops in Iraq that it did in a little over a month at Normandy. This is not to trivalize the losses this country has incurred in Iraq. The families of those who have died are suffering every bit as much now as they did six decades ago. The point here is that our nation's patience is a lot thinner than it was 64 years ago.
It is true that we have lost more than 4,000 troops in Iraq. But it is also true that we lost more than 400,000 troops in WWII.