A former prison officer said the violence behind bars made him feel like he was «fighting for his life.»
The officer described «horrendous» assaults on staff, violence between inmates and self-harm.
Prison inspectors have raised concerns about overcrowding as the prison population has risen 8% to 88,225 over the past year.
The Prison Service said it had invested £100m in prison security and was hiring more staff.
The prison officer, who wished to remain anonymous, said one officer sometimes had to supervise up to 30 prisoners, with rival gangs waging a «turf war» inside the jail.
He told the BBC’s Politics North programme: «They are not innocent people, you know they have all been convicted of crimes.
«And at that point they didn’t care if it was a prison officer. I’ve seen them suffer serious injuries, broken jaws, all that kind of stuff, headlocks, beatings.»
He added: «There are alarm systems in prisons, but if the prison doesn’t have staff available to respond to that then it’s dangerous.
«You’re alone and you feel like you’re fighting for your life.»
Ministry of Justice figures from April 2022 to March 2023 show that assaults on prisoners amount to 185 per 1,000 prisoners, with 82 attacks on staff per 1,000 prisoners.
During the same period there were 733 incidents of self-harm per 1,000 prisoners and a total of 88 deaths.
Charlie Taylor, chief inspector of prisons for England and Wales, said he was “hugely concerned by what we are seeing in many of the prisons we go to”.
«Our problem is that there are too many people for the number of places in prison,» he said.
«Ultimately, the number we send to prison is for the courts and ministers to decide, but as far as we are concerned, prisons are overcrowded and that means they cannot perform their rehabilitative function and that carries the danger of There will be more crimes.
«People who could be helped are not helped and will come back and wreak havoc on their communities.»
Last month, Justice Secretary Alex Chalk announced that prisons would be allowed to release some «less serious offenders» on parole early to relieve overcrowding.
A Prison Service spokesperson said: “Prison officers work day in and day out to rehabilitate offenders and protect the public, so it is vital they have the tools to do their job and keep them safe.
“That is why we have invested £100m in prison security, including x-ray body scanners and new body cameras.”
They added: «We are also doing more than ever to attract and retain the best staff, including increasing salaries, launching our first national recruitment drive and providing extensive mental health support.»