The teenager died at the scene after the attack
A man who killed a teenager sent text messages to an accomplice calling for support, the Old Bailey has heard.
Nabeer Bakurally, 19, from Forest Gate, east London, was stabbed in Ilford last November.
The court heard Abdul Siddique, 24, was the instigator of the attack, during which he wielded a large knife.
Mr Siddique has pleaded guilty to murder. Two others, Kalam Mohammed Kazi, 23, and Pradip Mistry, 22, deny the charges. All are from east London.
Aftab Jafferjee QC said Mr Bakurally was killed in a "sustained and brutal attack" in the early hours of Saturday. November 8.
A 17-year-old also suffered stab wounds but survived, he said.
Mr Jafferjee said the two victims were making their way home having spent the night around Ilford town centre.
"In a tragic turn, which might well have stemmed from a case of mistaken identity, their fate was sealed when they confronted three older males," he told the jury.
He said the confrontation was instigated by Mr Siddique who had sent messages to Mr Kazi, including one that read: "I'm a one man soldier from beginning to the end".
"That piece of bravado, the one man soldier, was not to last. It became three," he said.
He said the accomplices had received a text message which was effectively "a call to arms".
The jury was shown CCTV footage of Mr Bakurally, who was originally from Mauritius, and his friend walking along.
Counsel said Mr Siddique had two knives, including one which was large and "fearsome".
He said the three were accused on the basis that were "jointly liable".
"It is gang activity which enables this kind of attack to take place," he said.
They ran off following the attack and were later arrested, Mr Jafferjee said.
All three defendants are also charged with grievous bodily harm with intent.
Mr Siddique has pleaded guilty to the charge and will be sentenced at a later date for both charges.
Mr Kazi and Mr Mistry deny the charge.
The trial was adjourned until Tuesday.