Terrance Cameron, 67, suffered a fractured skull, broken nose and a possible fractured cheek in the alleged attack at his Buckingham Road home about 8.30pm on Saturday.
Police claim a 31-year-old man punched a woman known to him to the back of the head during an argument on the street.
The blow caused her to fall to the ground where police claim the assault continued until Mr Cameron intervened.
Police say the man punched Mr Cameron to the face, causing him to fall backwards and hit his head on the road.
He then allegedly turned his attention back on the woman kicking her and hitting her with a piece of wood.
“The next-door neighbour was assaulting his girlfriend and my Dad’s intervened to try to break it up,” Mr Cameron’s daughter Terry said.
“He’s just punched him in the face and he has gone back and hit his head on the concrete.”
Mr Cameron’s teenage grandchildren also saw the shocking incident.
“Mum gave me her dressing gown and I put that under pop’s head to make sure he wasn’t laying on the gravel and concrete and stuff,” Olivia Geranis, 16, said.
Midland detectives arrested the 31-year-old man nearby about 11pm.
He was charged with aggravated grievous bodily harm, aggravated assault with intent to do grievous bodily harm and aggravated assault occasioning bodily harm.
The man is due to appear in Midland Magistrate’s Court on June 18.
This article originally appeared on PerthNow.