The UK is one of the only countries in the world with an entire regiment of detention specialists.
Personnel sentenced for up to two years are sent to Colchester's Military Corrective Training Centre (MCTC), but inside, it is unlike a prison.
At MCTC, Armed Forces provost staff work to transform detainees, getting them ready to return to service as personnel, or to return to the civilian world.
The centre, known by some as 'Glasshouse' or 'Colly', puts the emphasis on correction and has a low reoffending rate of 10%.
Despite minimal security, with no bars and no barbed wire, no-one has tried to escape for years.
When detainees arrive, they are searched and personal items taken from them.
Their pay is stopped and, like in prisons, privileges such as phone credit, money for the shop and parole can all be earned with good behaviour.
The staff wear greens, just like the detainees, and some have served sentences at MCTC themselves.
Lieutenant Colonel Lee Pearce, Commandant of the Military Corrective Training Centre said: "MCTC is unique.
"Many describe it as the military prison – it's not."
"We are the corrective training centre but we help soldiers, sailors and airmen make change – so that’s change so they can go back to the Army, Navy or Air Force... or go to transition out of service life into civilian street with a realistic prospect of employment by giving them some vocational skills."
The detainees spend their time either keeping up their military-based skills or in vocational training preparing to transition out of the military.
Inspection is at 08:00 each day.
Staff Sergeant Emma Mannion-Williams, Platoon Commander – Detention Company told Forces News: "If you’re having a bad day, it doesn’t matter as long as you’ve made your bed in the morning.
"As long as you’ve done one good thing for that day then the only way is up, effectively."
Eighteen-year-old Detainee Under Sentence (DUS) Oliver Jelley was given 90 days at MCTC and told Forces News he would have likely been sentenced for up to four years by a civilian court.
"Coming here is probably a lifesaver," he said.
"I think if I went to a normal prison I wouldn’t be at this place where I am now… in the state of mind that I am.
"I learned a lot of things while I’m here, sort of grown up. I’ve become mature in myself…I’m a much better person."
He says he made "a big mistake".
"I’d never do it again. Never," DUS Jelley adds.
SSgt Mannion-Williams says: "Whatever they’ve done to get here, I don’t really care.
"I’m here to make sure, that when they are here, they’re striving to be better, they’re motivating themselves, they’re motivating others, they are making sure they are ticking all the boxes that they need to tick in order to either go back to society as a better person, to be an active good citizen.
"Or go back to their regiment and for their chain of command to turn around and go: 'Do you know what, I can see the improvement, I can see that you’ve got the zeal, you’ve got that attitude to get back into the military green lifestyle that we all joined for.'"
The vast majority are at MCTC for minor offences - like going absent without leave, others have committed more serious crimes.
Lieutenant Colonel Lee Pearce, Commandant of the Military Corrective Training Centre explains why the Ministry of Defence (MOD) invests money in helping offenders.
"There’s a moral obligation to look after our people," Lt Col Pearce said.
"Our people are our core capability, everything we do in the military is about our people, but at a more macro level, it's about the investment the system has made in terms of training.
"We’ve invested in those individuals - why would we throw it away for what quite often is a silly mistake, is rule-breaking rather than law breaking?"
When MCTC was inspected by Her Majesty’s Chief Inspector of Prisons in 2004, the results were poor.
Afterwards, the centre reverted from a punitive approach to a more reformative one, producing glowing results in 2017.
Captain Robert Moffat, Officer Commanding A And D Company said: "Some detainees will be filled with dread prior to arrival.
"We’ve moved on, it's more than just locking an individual behind a door and drilling them and PT-ing [Physical Training] them – it's about unpicking their offending behaviour.
"The punitive aspect of their sentence is that loss of liberty and loss of pay – we're not here to exert any more punishment per day on them during the sentence.
Before detainees can leave, they have a 'haul-up' in front of the Commanding Officer.
"They’ve made a mistake; they realise it but they’re able to set the next chapter up," Lt Col Pearce told Forces News.
"It’s really rewarding to see that change."