A former prison officer at a riot-hit jail says he fears for the young, inexperienced staff still working there.
Keith Conway said he took early retirement from Wiltshire's HMP Erlestoke in 2016 because he and his colleagues feared for their safety.
The government "needs to start getting discipline back into prisons", he said.
The Prison Service says it is taking "decisive action" to tackle the jail's "long-standing challenges".
A lack of experienced staff, which "remained a concern", contributed to violence at the Category C prison near Devizes in 2016, a report following the disturbance found.
It also said drug use was a "blight" leading to "frequent life-threatening emergencies".
Just days later after it was published, fresh violence broke out with five prison officers seriously injured.
Mr Conway, who had 28 years' experience as a prison officer, said there was "no respect" within the prison, with inmates knowing there were too few staff to cope.
"I was frightened, you didn't know what you were walking into. Staff were getting injured and their mental health was going," he said.
"I fear for those people who are still there and I take my hat off to them for what they are doing."
He added it was too much to expect new officers aged 20 or 21 years old to "tell a man of 40 doing a life sentence what to do".
'Cut too far'
Conservative MP Robert Neill, the chair of the House of Commons Justice Committee, said the Prison Service had been "cut too far".
While crediting the government for recruiting more staff, he admitted "we are shedding experienced officers at the same time".
Mark Fairhurst from the Prison Officers Association added: "We're not prepared to put up with this violence any more. Things have got to change."
A spokeswoman for the Prison Service said staff recruitment and drug testing had increased to improve conditions.
"We know there are a number of long-standing challenges, which is why we've taken decisive action," she said.