The lesson learned (or that should have been learned) is that we never go to war without a clear and present danger to the US or its allies, never without a formal declaration, never without the people of this country being on board with the war, and never without a clear exit strategy. What did victory look like in Iraq? Like Iraq of today? Did we win or lose? What did we win? We spent a pile of money and spilled gallons of blood, and for what?