In 1808, Napoleon thought he "decided" the campaign in Spain by "dispersing the formal Spanish armies," but "had inadvertently encouraged the local populace to resort to guerrilla warfare". He still didn't solve the problem in 1810-1811 sending 300,000 troops into Spain. Spain's population was over 11 million.
"Mission accomplished" was the banner in 2003, Iraq's army was vanquished. Four years later about 150,000 troops are trying to quell guerrilla warfare in a country of over 27 million.
And George W. Bush isn't as good a commander-in-chief as Napoleon was. Unfortunately, they both share the characteristic of hubris, thinking they knew better than anyone else.
For a hopeful outlook, see "How to Win in Iraq, and How to Lose", by Arthur Herman, Commentary, April 2007, http://www.commentarymagazine.com/cm/main/viewArticle.aip?id=10856&page=all
Will George W. Bush put in the necessary diplomacy to make it work? Or will his strategy be lots of high-tech bang-bang?