Three teenagers have been jailed for 18 for the murder of 15-year-old Sofyen Belamouadden at Victoria Tube station in March 2010.
Sofyen was chased through the station and stabbed nine times during the evening rush hour. Obi Nwokeh, 19, Christopher Omoregrie and Samson Odegbune, both 18, were convicted of murder at the Old Bailey.
Old Bailey judge Christopher Moss gave each a life sentence and told the must serve a minimum old 18 years.
Nwokeh, Omoregrie and Odegbune were also ordered to serve concurrent eight-year detention sentences for conspiracy to cause grievous bodily harm.
Judge Moss said the "ferocious and merciless attack" took place in front of commuters.
"You gathered together for the purpose of serious mass violence in a busy public place at the height of the rush hour."
The promising footballer, whose ambition was to play for England, suffered wounds to his heart, a lung and major blood vessels during the 12-second attack, the court heard.
The attack followed a minor confrontation between pupils of two west London schools in the Victoria area.
Following messages by text and on Facebook, members of the defendant's school armed themselves with knives and a Samurai sword, expecting the other group to attack their school.
But the confrontation came at Victoria when members of Sofyen's school were charged by teenagers led by Odegbune holding the sword.
A breakaway group chased Sofyen into the Tube ticket office area and kicked, stabbed and struck him with other weapons as travellers watched in disbelief.
In total eight teenagers have been found guilty in connection with the death during a series of trials.
Adonis Akra, 18, Samuel Roberts, 19, and Femi Oderinwale, 18, were found guilty of manslaughter and given 12 years detention each.
Tyrone Richards, 17, and Enoch Amoah, 19, were convicted of conspiracy to commit grievous bodily harm and sentenced to seven years detention.
Victoria Osoteku, 19, the only woman charged in the case, was also found guilty of manslaughter. She will be sentenced next week.
Sofyen's mother Naima's statement said: "I hope the memory of what they did to my son lives with them every day as it lives with me."