The victim was leaving a music event at Wollaton Park, Wollaton Road, when he spotted a man and a woman arguing.
After approaching the couple and trying to act as a peacemaker, the man responded by punching the victim in the face before leaving the scene.
He was left with a fractured jaw and a black eye following the assault, which happened at some point between 11pm and midnight on 26 May 2023.
The attacker was described as white, around 6ft tall, and in his late 40s or early 50s. He was also bald and was wearing a white t-shirt, grey denim shorts and white trainers.
PC Megan Offiler, of Nottinghamshire Police, said: “This was a horrible assault that left a man who was simply trying to calm down a situation with serious facial injuries.
“We know this incident happened as the victim was leaving Wollaton Park and coming out onto the main road – at a time when an event being held there was coming to an end.
“As a result, this area would’ve been very busy at the time, so there will have been people who saw this assault happen with their own eyes.
“It is extremely important that these witnesses come forward, as any information they have could help us track down the man responsible for this assault.”
Anyone with information is asked to call the police on 101, quoting incident 537 of 27 May 2023, or contact Crimestoppers anonymously on 0800 555 111.
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