Police said at about 1am on Saturday (July 31), the 44-year-old man had been walking with a friend along St James’ Street and had just turned into a road off the main street, near the Co-op, when he was struck in the face with a bottle and then with a broken bottle, by each of two men.
He was then kicked in the chest and fell to the ground.
A Sussex Police spokesman said: “He was taken to the Royal Sussex County Hospital for treatment and was discharged later the same night.
“The man he was with was not hurt.
“Nothing was reported to have been stolen
“The two assailants, who are believed to have been with at least one other man, then made off along Margaret Street.”
Detective Inspector James Meanwell added: “The motive for this vicious though isolated attack has not been established and we are currently investigating to establish the full circumstances.
“Anyone who saw what happened is asked to contact the police either online or by calling 101, quoting serial 83 of 31/07.
“You can also contact the independent charity Crimestoppers anonymously on 0800 555 111.”