A solicitor who defended an inmate who took part in a prison riot said the case highlighted a lack of staff.
Luke Needham, 30, Deno Harrison, 23, and Ben Sharratt, 27, each had three years added to their sentences following the disturbance at HMP Erlestoke in Wiltshire in June 2016.
Solicitor Greg Foxsmith said, at the time of the riot, there had been 17 staff guarding more than 500 inmates.
The Ministry of Justice said more staff had since been recruited at Erlestoke.
During the trial last month, Winchester Crown Court heard the mutiny began after staff shortages led to inmates being kept in their cells.
It caused £850,000 worth of damage and led to 120 prisoners having to be re-housed.
Needham and Harrison, who were found guilty of prison mutiny, and Sharratt, who admitted the offence, were sentenced on Friday.
Mr Foxsmith, who defended Needham, said: "I don't think any of the defendants expect any sympathy but one of the interesting things through the trial is that it did throw out a number of issues.
"There were terrible funding cuts in the prison service leading up to the disturbance and, in fact, on the day of the disturbance there were only 17 members of staff on duty which is not nearly enough to maintain control in a prison of over 500."
The Ministry of Justice said the sentences demonstrated it would not tolerate violence in prisons.
A spokesman said it had recruited more staff at Erlestoke, near Devizes, and additional measures, such as body-worn cameras, new-style handcuffs and PAVA spray - similar to pepper spray - were being trialled or introduced.