The victim, a 52-year-old man from Bedford, was punched to the floor during a fight “involving several people” at Butlin’s Bognor Regis on Friday (14 June), according to Sussex Police.
He was taken to Royal Sussex County Hospital in Brighton where he died on Tuesday afternoon (18 June).
Detective Chief Inspector Andy Wolstenholme said: “A fight at a holiday park, which involved several people, sadly resulted in the death of a man. We extend our sympathies to his family and friends at this difficult time, and are providing support with specialist officers.
"The bar was very busy at the time of the assault and we believe many of those present would have witnessed the assault and the aftermath. We have spoken to some witnesses who were present at the time, but we would be keen to speak to anyone who hasn’t yet made contact with us. Enquiries are ongoing.”
A 31-year-old man from Wandsworth, south London, has been arrested on suspicion of causing grievous bodily harm with intent. He has been bailed until 13 July.
Anyone with information is asked to call Sussex Police on 101 quoting Operation Brockton, or report any information online via the Sussex Police website.
Alternatively, anyone with information can contact independent charity Crimestoppers anonymously on 0800 555 11 or via the Crimestoppers website.