Jason Sullivan, 34, from Essex, was arrested in Padholme Road on October 18, 2020 after police received reports of a burglary in progress and an assault.
At about 7pm, Sullivan visited the victim's home and struck him over the head with a metal ratchet.
The force of the blow knocked the man, who is in his 30s, to the floor but Sullivan continued his attack.
The victim's partner tried to pull Sullivan away, but when he didn't stop she ran to neighbours for help.
Two neighbours came to their aid and managed to restrain Sullivan until police arrived.
Sullivan, of Meadowgate Avenue in Chelmsford, was initially charged with aggravated burglary which he denied, but pleaded guilty to a lesser offence of attempting to cause grievous bodily harm (GBH) with intent.
He appeared at Cambridge Crown Court on Monday July 19, where he was sentenced to three years and eight months in prison.
DC Kieran Dolman, who investigated, said: “This was an extremely violent attack which although it has not left the victim with any long-term injuries, it has left him with permanent scarring on his head.
“We do not know why this happened, but regardless of the reason, no one should ever have to endure such violence, especially in their own home.
“Understandably this has had a significant impact on him and his family, including his young children who were in the house at the time of the attack.
“I hope this sentence provides them with some reassurance and they can start to move on from the trauma.”