Paul McArthur assaulted his partner at their home in Otley Terrace, in Darlington, in the early hours of May 31 this year. The attack was witnessed by neighbours who attempted to intervene.
After smashing a mobile phone belonging to a passer-by who had stopped to help, McArthur picked up a large kitchen knife and brought it out into the street where he chased one of the men before stabbing him in the back, puncturing his lung.
McArthur fled the scene, but handed himself in a short time later after a social media appeal for information on his whereabouts was posted on a police Facebook page.
He was charged with wounding with intent, assault by beating, criminal damage and threatening a person with a bladed article.
The 39-year-old, of Otley Terrace, Darlington, pleaded guilty to the offences and was jailed for six years at Teesside Crown Court earlier this week.
Detective Constable Stewart Walker, from Darlington CID, led the investigation. He said: “The victim in this attack suffered a serious injury for simply trying to be a Good Samaritan and stop an assault from escalating.
“He received hospital treatment for his injuries, but thankfully he is set to make a full recovery.
“I am pleased that McArthur has admitted his guilt and is now behind bars – I hope this provides his victim with some comfort, knowing that he is off the streets and unable to cause any more harm.”