Prison staff are attacked on average 23 times a day as surging levels of violence continue to sweep through jails in England and Wales.
Ministry of Justice figures revealed there were 29,485 assault incidents last year and self-harm behind bars climbed to a record high.
Within that figure, there were 8,429 assaults on prison staff in the 12 months to December, a year-on-year rise of more than a fifth (23%).
Of the attacks on officers, 864 were classed as "serious" - such as those which require medical treatment or result in fractures, burns, or extensive bruising.
There were 44,651 incidents of self-harm among inmates last year, up by 11% compared with 2016, while the number of self-harming individuals increased by 6% to a new record high of 11,630.
In the year to March, there were 299 deaths in prison custody, a year-on-year fall of 13%. There were 69 self-inflicted deaths, down from 115 in the previous year.
The findings on assaults and self-harm underline the scale of the safety crisis that has gripped much of the prisons estate in recent years.
The Ministry of Justice report noted there has been a change in how assaults on staff are recorded, which may have contributed to the increase.
Justice Secretary David Gauke acknowledged that levels of violence are "far too high" and said the Government is taking "urgent action to address these problems".
He said: "Assaults on our hardworking staff will never be tolerated.
"We are ensuring prison officers have the tools they need to do the job, rolling out body worn cameras, 'police-style' handcuffs and restraints, and trialling PAVA incapacitant spray."
He added that recruitment is "vital to ensuring prisons are safe, secure and decent" and told how "3,111 new prison officers are due to be on landings by the summer."