Sean D Naylor of the American Army Times quotes a US soldier describing the fighting as so intense that "it looks like Apocalypse Now".
Naylor reports the destruction of American tanks, rocket-propelled grenade assaults and deadly air strikes called in on the Iraqi attackers.
So intense was the fighting that at one stage the 3rd Squadron commander's driver, Private First Class Randall Duke Newcomb, was forced to steer his Humvee with one hand while firing out of the window with the other.
The battle on the Euphrates came when a US armoured column of the 7th Cavalry was caught in a deadly ambush by hundreds of Iraqi soldiers on the road to Baghdad at Najaf.
Although first reports suggested there were no American dead, intelligence sources in Washington say it is feared the Allies may have taken "heavy casualties".