"On 20 March 2003, coalition forces crossed the Iraqi border heading straight for the heart of Baghdad. It had been 30 years since the US Army had pulled truck companies out of Vietnam and had forgotten all lessons on convoy security from that war. Having accepted much of the media myth about the Americans losing the war, many senior Army officers were reluctant to accept any solution from that war. In fact the major lesson learned from that war was that the United States would never again find itself fighting an insurgency."
Government Publishing Office: https://www.gpo.gov/