A coroner said lessons must be learned after a series of mistakes led a US Apache helicopter to attack a British base in Afghanistan.
Lance Corporal Christopher Roney, from Sunderland, died in the onslaught at Patrol Base Almas in Sangin, Helmand, on December 21, 2009.
Sunderland Coroner Derek Winter listed a series of errors.
He said: “L/Cpl Christopher Roney died as a consequence of assumptions made, mistaken beliefs and cumulative failures by friendly forces.”
He will write to Defence Secretary Philip Hammond and said “lessons must be learned”.
The 3rd Battalion The Rifles soldier was fatally injured during a fight with the Taliban after the enemy detonated a huge bomb.
His platoon was holding off the attack when, without their knowledge, two US gunships were called in to help. One fired 200 rounds into the base because the air crews had been told it was an enemy position.
When British Army staff saw pictures beamed from a camera on an unmanned drone they misidentified the base, which was not on official maps, and guided the Apaches to the location. Soldiers fired mortar illumination to light up the battle zone, but this was mistaken for enemy fire.
Staff at another base watched the scenes unfolding, but they failed to recognise Almas because its appearance had been changed by the Taliban bomb. The “total disorientation” led commanders to authorise the Apaches to attack with 30mm chain guns.
Mr Winter appreciated the conditions were “extremely challenging” but said the exemplary action under pressure by L/Cpl Roney and his comrades had not been matched by staff elsewhere.
Seven soldiers were badly injured. L/Cpl Roney was flown to Camp Bastion but died next day.
Injured soldiers could sue the Ministry of Defence for negligence but no one will face prosecution.
L/Cpl Roney left a widow, Lorna, and baby son William.
Afterwards the family criticised the Ministry of Defence in a statement which said: “We believe the documentation has been written and worded cleverly to make this incident look a lot less serious than what it actually was.
“This has upset the family considerably and gives the family the impression that Chris and his comrades who were injured that night mean very little to the Army.”
An MoD spokesman said the incident occurred in a highly challenging and fast-moving operational environment.
“All of those involved acted with the best intentions to assist their comrades, but tragically mistakes were made.
“Comprehensive investigations have been conducted and key lessons identified.”