Detectives arrested a 30-year-old man from Dover on suspicion of assault on Sunday 8 August 2021.
He has been released on bail pending further enquiries.
Kent Police was called to the rear garden of a pub in Crabbe Avenue in River following a report a man had been assaulted by another during an altercation at around 7.40pm on Sunday 30 May.
The victim, a man in his 30s, suffered a head injury which required hospital treatment.
A 38-year-old man who was arrested on 8 June in connection with the incident remains under investigation.
Investigating detectives would like to thank those who have already come forward with information and are appealing for any witnesses who have not yet spoken to an officer to contact Kent Police on 01843 222289 quoting 46/92609/21.