A British soldier "enjoyed" hearing Iraqis call out in pain as they were kicked and punched while in a detention centre, a court martial has heard.
Baha Mousa died in custody after being arrested in Basra
British Cpl Donald Payne referred to the noises made as "the choir", which he "conducted" in front of visitors to the centre, said a prosecuting QC.
The 35-year-old admits inhumane treatment but denies manslaughter.
Six other soldiers have pleaded not guilty to charges relating to the death of Baha Mousa, 26, in Basra in 2003.
This week Cpl Payne became the first British soldier to admit to a war crime after pleading guilty to the inhumane treatment charge.
He has denied a further charge of perverting the course of justice.
The charges brought against the seven soldiers also relate to the alleged ill-treatment of other detainees.
Prosecutor Julian Bevan QC said Cpl Payne seemed to carry out his "conductor" role without fear of repercussion.
"The choir consisted of Cpl Payne systematically assaulting each detainee in turn by, for instance, hitting in their stomachs, kicking them and punching them wherever on their bodies, causing them to shriek out or groan in pain, their various noises constituting the music," he said.
The corporal also shouted expletives while trying to force the prisoners into a "stress" position prior to questioning, the court martial - held at the Military Court Centre, Bulford Camp, Wiltshire - was told.
Groans of pain from the detainees were heard on a film, recorded by another soldier and shown in court.
Mr Bevan added that guards watching over the Iraqi prisoners were taking their orders from Cpl Payne "for the most part".
He "led by example", said Mr Bevan, using force that was "both unnecessary and at times excessive".
Mr Mousa, a hotel receptionist, was among a group of detainees arrested following a counter-insurgency operation.
They were taken to a temporary detention centre where they were held for 36 hours and repeatedly beaten while handcuffed and forced to wear sacks on their heads, Mr Bevan said.
CHARGES IN FULL
Cpl Donald Payne - manslaughter, inhumane treatment of persons, perverting the course of justice
L/Cpl Wayne Crowcroft - inhumane treatment of persons
Pte Darren Fallon - inhumane treatment of persons
Sgt Kelvin Stacey - actual bodily harm, alternatively assault
Warrant Officer Mark Davies - negligently performing a duty
Maj Michael Peebles - negligently performing a duty
Col Jorge Mendonca - negligently performing a duty
Mr Musa died from his injuries, the court was told.
L/Cpl Wayne Crowcroft, 22, and Pte Darren Fallon, 23 - both also of the Duke of Lancaster's Regiment - deny the charge of inhumane treatment.
The charge faced by the three is being brought as a war crime charge under the International Criminal Court Act (ICCA) 2001, for the first time under the new law.
Sgt Kelvin Stacey, 29, of the Duke of Lancaster's Regiment, is accused of assault occasioning actual bodily harm with an alternative count of common assault.
Maj Michael Peebles, 35, and Warrant Officer Mark Davies, 37, both of the Intelligence Corps, face charges of negligently performing a duty.
And Col Jorge Mendonca, 42, formerly commander of the Queen's Lancashire Regiment - which is now renamed as the Duke of Lancaster's Regiment - is charged with negligently performing his duties.
Mr Bevan told the court Pte Fallon and L/Cpl Crowcroft were put in charge of guarding the detainees on the first day of their imprisonment.
It is alleged another soldier witnessed them punching and kicking one man who had fallen on the ground.
"According to the Iraqi detainees themselves, they were constantly beaten, be it by kick or punch, from the moment they arrived, throughout that Sunday and certainly until the death of Mr Mousa that Monday evening," Mr Bevan said.
Pte Fallon and L/Cpl Crowcroft were later said to have bragged about the assaults and about injuries to their own knuckles and feet, he told the court.
During a drunken conversation in Cyprus in 2005, L/Cpl Crowcroft told a fellow soldier he was worried about the investigation into the treatment of Mr Mousa, because "we all kicked him to death", the court was told.
The court has also heard an Iraqi man kicked and punched by Sgt Stacey, 29, was later taken to hospital suffering from kidney problems.