American and British forces in Iraq suffered their worst day of the war yesterday when up to 10 marines were killed, 12 were missing in action and 14 wounded, write Lara Marlowe in Baghdad, Conor O'Clery in New York and Deaglán de Bréadún in Doha.
A Royal Air Force Tornado jet was shot down accidentally by an American anti-missile battery. Both crew died. One US marine died and 15 others were injured when a US soldier, for unknown reasons, threw a hand grenade into their tent.
American confidence was further dented last night when Iraqi television showed captured American soldiers and the corpses of several others.
The tactic angered the Bush administration. Self-confident speculation about a quick and decisive victory over a demoralised enemy gave way to a mood of foreboding about difficult days ahead for the US.
President Bush warned Americans that "this is just the beginning of a tough fight".
In his weekend radio address, Mr Bush advised them that "a campaign on harsh terrain in a vast country could be longer and more difficult than some have predicted."
Mr Bush said: "I can assure the American people that we are making good progress and I can also assure them that this is just the beginning of a tough fight.
"It's important for American people to realise that this war has just begun.
"We're slowly but surely taking control of that country so that we can free the people of Iraq and eventually clear the country of weapons of mass destruction."
US Defence Secretary Mr Donald Rumsfeld also admitted that "there have to be tough days ahead, war's unpredictable, a large number of things can still go wrong."
A number of the American prisoners of war were shown being interviewed on film believed to have been shot by al-Jazeera TV. These were the first US prisoners known to have been taken by Iraq since the start of the war.
They were from a vehicle repair unit, the 507th Maintenance Company, from Fort Bliss, Texas, rather than a combat outfit.
One of the soldiers said he had nothing against Iraqis.
He said: "I just followed orders. I came to fix broke things. I don't want to kill anybody."
Asked what he thought about the Iraqi people, he said: "They don't bother me, I don't bother them."
A soldier lying down was helped lean forward. "Edgar, my name is Edgar," he said.
Another soldier, wearing wire-rimmed glasses, who identified himself as "Private First Class Miller", was asked why he had gone to Iraq. In a strained voice, he said: "I was told to come here."
Another soldier, clearly more nervous and bewildered, his hands folded between his legs, his head turning slowly from one questioner to another, gave his name as Sergeant James Riley (31), from New Jersey.
Also interviewed was a black woman, who gave her name as Shawna (30), who had a bloody bandage on her left ankle.
The atmosphere throughout all the interviews appeared tense, with the prisoners of war uncertain and confused by the halting English of the interviewers.
The interviews outraged Mr Rumsfeld, who said they contravened the Geneva Convention, a view shared by the British Prime Minister, Mr Tony Blair, who said they were a "flagrant violation" of the convention's provisions.
However, President Saddam Hussein said the prisoners would be "respected and treated under the Geneva Convention" even though last week, his Information Minister, Mr Muhammad al-Shaf, said captured Coalition troops would be treated as "criminals and mercenaries" and would not be afforded any such protection.
The dead marines shown on TV are believed to have been killed at Suq al Shuyakh during fierce fighting for control of Nassiriya, a key city on the Euphrates, about 100 miles north of Basra.
The POWs were captured apparently after their armoured vehicle took a wrong turning.
Further south, sporadic fighting continued yesterday at the port city of Umm Qasr and Basra remained surrounded by Coalition forces but not wholly taken.
US forces halted their drive north to Baghdad just outside the city of Najaf.
The capital took another pounding from the air as the city became enveloped in smoke after trenches of oil were set alight.
Coalition forces say they hope to reach the city within 36 hours.
The regime is promising to defend the city street by street.