Soldier Lee Rigby was run over and attacked with a knife and meat cleaver in "a cowardly and callous murder", a court has heard.
Video footage of the Fusilier being mown down and two men dragging his body into the middle of the road was shown to jurors at the Old Bailey today.
It is claimed that Michael Adebolajo, 28, tried to decapitate him, while Michael Adebowale, 22, stabbed him. One eyewitness described their actions as being "like a butcher attacking a joint of meat".
Fusilier Rigby's widow Rebecca left the court room in tears before CCTV clips were played showing her late husband being run over.
There were gasps in oak-panelled Court Two of the Old Bailey as the footage was shown, prompting more of the soldier's relatives to leave.
Prosecutors claim that Adebolajo and Adebowale wanted members of the public to see what they had done.
Richard Whittam QC told the court: " They wanted members of the public to see the consequence of what can only be described as their barbarous acts.
"They had committed, you may think, a cowardly and callous murder by deliberately attacking an unarmed man in plain clothes from behind, using a vehicle as a weapon, and then they murdered him and mutilated his body with that meat cleaver and knives."
The first piece of footage showed a Vauxhall Tigra, which prosecutors claim was being driven by Adebolajo, swerve across Artillery Place in Woolwich, south-east London, and mow down the fusilier. Other footage showed the two men dragging his body into the road.
The jury was told that the car was driven "straight at" Fusilier Rigby at a speed of 30-40mph, before the knife attack.
Eyewitness Amanda Bailey, who saw the events from inside her Peugeot 206, said one of the attackers looked as if "he didn't care".
Mr Whittam told the jury: "As she put it, 'I was so shocked that all I could do was sit there and stare at what was happening. I couldn't believe what was going on. He was determined and he wasn't going to stop. He didn't care'."
The prosecutor told the jury that members of the public showed "bravery and decency" in the aftermath of the alleged attack.
He went on: "Such heinous behaviour is in distinct contrast to the bravery and decency shown by some of the members of the public present. Despite the abhorrence of the scene, one woman went to the lifeless body of Lee Rigby and stroked him to provide some comfort and humanity to what had unfolded. Others went to see if they could provide first aid.
"Another woman engaged Michael Adebolajo in conversation despite the fact that he was still holding the meat cleaver and his hands were covered in blood."
The court heard that the two men were also armed with a gun, and have admitted possession of a firearm with intent to cause fear of violence.
Mr Whittam told the jury of eight women and four men that the firearm was part of the plan the pair had made, and was used partly to frighten off members of the public before the emergency services arrived.
As a police vehicle swung into Artillery Place, both men moved towards it, Mr Whittam said, and Adebolajo raised the meat cleaver above his head.
He and Adebowale were both shot by police and arrested, the court heard.
They are both accused of attempting to murder a police officer, and conspiracy to murder a police officer on or before May 22.
Mr Whittam told the court the defendants had been together for five hours before the alleged murder and added "it was clear" there had been an agreement to attack the police when they arrived.
The events took place within yards of Mulgrave Primary School, the court heard , to which children were returning from a visit to the library. Members of the public turned them back to avoid the "awful" scene.
A number of women went to the scene to comfort the soldier, the jury heard, including Amanda Donnelly Martin, who was with her daughter.
The court heard that Adebolajo handed her a letter containing religious references.
It said "to fight Allah's enemies is an obligation" and went on: "If you find yourself curious as to why carnage is reaching your own towns then know it's simply retaliation for your oppression in our towns."
The handwritten note continued: "Whereas the average Joe Bloggs working class man loses his sons when they're killed by our brothers, when the heat of battle reaches your local street it's unlikely that any of your so-called politicians will be at risk or caught in crossfire so I suggest you remove them."
Jurors were also shown a video clip of Adebolajo speaking with blood on his hands, suggesting that the attack was "an eye for an eye".
He said: "The only reason we've killed this man today is because Muslims are dying daily by British soldiers.
"This British soldier is one - he is an eye for an eye and a tooth for a tooth."
But Mr Whittam told the jury: "T here is no defence of moral justification for killing just as there is no defence of religious justification. An eye for an eye and a tooth for a tooth suggests revenge or retaliation, and in the context of this case, murder."
Mr Whittam told the court that Adebolajo made a number of comments after he was shot by police.
These included: "I am a Muslim extremist, this may be the only chance you meet one."
He also wrongly claimed that Fusilier Rigby, who was wearing a Help for Heroes hooded top, was in military kit when he was attacked, the court heard.
He said: "My intention was never to hurt civilians. There were women and children around. My intention was to hurt military only. He was in his kit, in his uniform, coming in and out of the barracks."
The trial was adjourned until Monday.