A man who left a pensioner with head injuries after a "one push" assault has been jailed for 12 months.
Christopher Ivison, 29, from Middlesbrough, left the 75-year-old man unconscious after the attack in Ely, Cambridgeshire in July.
The victim had a bleed to the brain and still has problems with his hearing and speech, police said.
Ivison pleaded guilty to inflicting bodily injury without a weapon at Cambridge Crown Court.
Police said Ivison, of Trimdon Avenue, had been visiting Ely for the weekend and had been "under the influence" when the assault took place on the city's Market Square at about 00:30 BST on Sunday, 8 July.
The victim was unknown to him, they added.
Ivison fled the scene and officers arrived to find the 75-year-old unconscious in the road and bleeding from the back of his head.
He was diagnosed with a bleed to the brain and spent three months recovering in a care home.
His hearing and speech are still affected.
Det Con Neil Gibbs, of Cambridgeshire Police, said: "Ivison may not have realised the true force of his assault as he was under the influence, but this is no excuse.
"His actions left the victim with serious head injuries and demonstrates the dangerous consequences one push can have."