Padraig Nally, 61, had been found guilty of the manslaughter of father-of-11 John Ward at his 65-acre farm in Cross, County Mayo, in October 2004.
Mr Justice Paul Carney told Dublin`s Central Criminal Court that it was the most difficult trial he had to sit through in his 40 years in the courts.
Sentencing Nally to six years, the judge said: "This is undoubtedly the most socially divisive case I have had to try. It is also the most difficult one in which I have had to impose sentence."
The judge said he would take into consideration Nally`s unblemished past, his low-risk of re-offending, his willingness to show remorse for his crime and the fact that the prosecution`s case was based largely on testaments given by the farmer.
"It`s for me to balance all these matters to which I have referred as best as I surely can," the judge said.
"I have found this the most difficult sentencing matter that I have had to deal with for 40 years."
The court was told Nally arrived at his farmhouse on the afternoon of October 14, 2004 when he spotted a suspicious-looking car parked beside an overgrown lane next to the house with a man sitting in the driver`s seat.
The court heard that Nally had become increasingly agitated and worried that his property would be targeted by local thieves as a number of farms in the area had recently been burgled. His own home had been broken into in 2003 and a chainsaw stolen from one of his sheds in February 2004.
Friends and neighbours noted Nally had become preoccupied with looking after his farm and terrified that the robbers would return.
The court was told Nally approached the vehicle and told the driver that whoever was on his land would not be coming back.
When he checked around the farmhouse, the court was told Nally discovered 42-year-old Mr Ward at his back door.
The farmer grabbed a loaded shotgun from one of the sheds and shot Mr Ward in the side.
Garda sergeant James Carroll, one of the first officers on the scene, told the court there was no forensic evidence to show that Mr Ward had been in Nally`s house.
The court heard that after shooting Mr Ward, Nally shoved him into a bed of nettles. He then beat him repeatedly with a two-foot stick. Mr Ward tried to run away, limping and bleeding from the shotgun wound. He struggled to make it off Nally`s land, the court heard.
Sgt Carroll said Nally went back his shed and loaded the single barrel shotgun.
He followed Mr Ward to the edge of the land and as he tried to flee, Nally shot him a second time. He then dumped the body over a wall.
The court also heard that Nally returned to his house but minutes later called at a neighbour`s home and confessed to the brutal killing.
Throughout the Garda investigation, Nally was said to have been open and candid about what had happened. But the court was told Nally told officers he had been out of his mind with fear and that he felt suicidal after shooting.
Mr Justice Carney said Nally had attacked Mr Ward as he retreated from the farm but he also conceded Nally had shown a great deal of remorse over the attack.
Friends described Nally as a great neighbour and someone who could be relied on for help at any time. Neighbours said his door was always open.
Michael Varley, a next door neighbour who had known Nally all his life, said: "Padraig Nally was a great neighbour always to the community. If you wanted something done, not a bother, you`d go to Padraig Nally and he`d leave his own work and go and help you."
The court heard Nally had become anxious, depressed and felt under pressure from the threat of burglars but a psychology report also concluded that Nally was conscious, sensitive and sympathetic to the Ward family who had lost a husband and father.
The court heard that a post-mortem examination and toxicology tests on Mr Ward`s body found traces of cannabis, opiates and tranquillisers. It was also emphasised that Mr Ward had been receiving hospital treatment and was on medication for a condition.
His widow, Marie, told the court: "I am lost since my husband`s death, I will never be the same without my husband."
She said she had suffered from poor health since the killing, with high blood pressure, diabetes and was taking medication and counselling for depression.
Mrs Ward told the court two of her eldest children had begun harming themselves since the death with one son currently in a psychiatric unit.
"Are things improving?" she asked. "Things are not improving, they are getting worse every day.
"My youngest is four. He says to me `where is my daddy, when is he coming back? What can you say to my son?"
Mrs Ward said she had received huge support from the traveller community and some support from settled families in the area.
During his trial, Nally told the court that he had been subject to constant calls from travellers asking if he had anything for sale.
Nally said he could no longer live with the constant stress of strangers on his land and visiting his home.
The court also heard Nally had never been in trouble with the law, but Mr Ward had 12 previous convictions for burglary, possession of stolen goods and other offences.
At the time of his death he was facing charges of attacking police officers with a slash hook.
Outside the court Martin Reilly, brother-in-law of Mr Ward, said the family were very disappointed with the six-year prison term.
"We are very disappointed, I think a man`s life is worth more than six years," Mr Reilly said.
"It`s something that we`ll never get back, a loving husband, a loving father, a loving man in every way.
"John Ward was a decent man, an honourable man and a loving man."
Mr Reilly also claimed there had been a vendetta in the local community against travellers.
"I don`t think it at all, I`m 100 per cent sure it is," he said.