A dad granted custody of four sons after having them taken off him due to disgusting living conditions went on to repeatedly assault them.
The 44-year-old, who cannot be named as that would identify his victims, was jailed in 2014 because of his family's "extremely dirty" house.
Police discovered cat urine, faeces, used nappies and rubbish littered around the home, little food, and no bedding on the children's beds.
But after the dad served his sentence and completed courses in parenting and domestic violence, the children were returned to his care.
Liverpool Crown Court heard he then repeatedly punched, smacked and slapped his four children and grabbed them around the throat.
The man and his wife both admitted child cruelty in 2014, after their property was deemed uninhabitable and dangerous for the children.
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Three of the youngsters were found asleep in various stages of undress, while the youngest – a baby – was lying in a Moses basket on top of a bed.
The boys were removed by Social Services and placed into foster care, while their dad was jailed for 12 months, later reduced to six months on appeal.
Upon his release from prison, he engaged with the Probation Service and the council to complete the courses and received positive feedback.
As a result, Social Services agreed the children could be returned to live with him in 2015 and monitored the family under a care order until 2018.
However, towards the end of that order and after it ended, his violence against the boys escalated, some of which was witnessed by other children.
The dad always denied any wrongdoing, but was found guilty of four offences of child cruelty after a trial in March this year.
The eldest child told a jury he was punched at least five times when naughty, smacked at least once every day when someone did something wrong, and if he was really naughty, "hit really hard" on his arm and bottom.
He described one occasion when he was picked up by the throat, said the violence got "worse and worse", and he was left scared with bruises and red marks.
The second eldest boy said he was slapped "super hard" and "everywhere", leaving bruises to his arms, legs and body.
The third eldest son described being slapped and hit leaving marks to his body, "strangled" when his dad pulled his and his brothers' shirts, so they dug into their necks, and being punched in the stomach and legs.
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The youngest boy said he was slapped very hard, grabbed by the collar, and slapped to his cheeks, causing redness.
A child witness described how the dad chased the boys around the house when angry, hit them even if they did something wrong by accident, and would leave them in tears.
Judge Garrett Byrne, who presided over the trial, told Kyra Badman, prosecuting, that he did not require her to formally open the case at a sentencing hearing yesterday, as he had already heard enough.
Peter Horgan, defending, said his client still denied the offences, so there was very little he could say about them.
He said the dad had suffered "quite serious mental health problems" and was referred to mental health services due to "concerns about his suicide risk".
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Mr Horgan said references showed he had a non-formal caring role for his mum, who had health issues, and if jailed the impact on her would be "significant".
He said the dad also acted in a caring role to a man with health issues sitting in the public gallery, and to his sister, who again had "medical difficulties".
Mr Horgan told the court references from an ex-partner and her adult children pointed to a supportive person and showed "another side to this man".
He said the Probation Service was willing to support him and provide appropriate courses if the judge was willing to spare him jail.
Judge Byrne referred to the dad's previous sentence for a different form of cruelty and the courses he previously undertook.
He said: "It's apparent that those courses and your conviction were insufficient to cause you to change your ways because you continued to be cruel towards these boys."
The judge added: "Your role and responsibility as a parent was to keep these children safe from harm and to create a warm, nurturing and loving environment.
"Instead you were unable to control your temper and you subjected them to constant physical abuse that went well beyond what could be described as reasonable chastisement."
Judge Byrne said the "naughty behaviour" of the boys described was "nothing outside the ordinary range of misbehaviour for children of their age".
He said the case was aggravated by the fact the dad knew they were vulnerable and some had developmental challenges, yet he "regularly punched them and smacked them on their bottoms, arms, legs and faces, with considerable force".
The judge said: "There is evidence from which the court can conclude the boys suffered serious psychological and emotional harm."
Judge Byrne, who saw the boys give evidence, said: "They were clearly upset about what happened to them. They were confused as to why their own father would behave to them in this way."
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The boys' mum – who the judge found to be a "credible witness" – said the eldest child now had anger problems and was violent, which she felt was "copying behaviour", and was referred to mental health services.
The second eldest child, who was diagnosed with anxiety due to his trauma and referred for counselling, suffered nightmares, emotional breakdowns and didn't want to leave the house, for fear of bumping into his dad.
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The two other boys both suffered nightmares and wet the bed, while the youngest was also described as having anger issues.
Judge Byrne took into account the dad's physical and mental condition, and the impact on others of sending him to prison.
But he said that was the only appropriate punishment and jailed him for four and a half years.