A peacemaker from Belfast suffered a broken jaw after his attempt to break up a fight provoked a violent reaction outside a pub in Waterloo Street.
Police at Strand Road are appealing for information about the assault on the man in the city centre.
The incident happened at about 1am on January 31 outside a public house at Waterloo Street. The man, who is aged 27 and from Belfast, sustained an injury to his head.
Constable Johnston, the investigating officer, said two groups of males fell out outside the bar and a man stepped in to break up the fight. This resulted in him being punched to the ground and subsequently receiving six stitches to the back of his head and a fractured jaw.
Anyone who can help identify the offenders is asked to contact police on 101.