A number of men were taken to hospital following a fight at a Bridge Street bar in the early hours.
Police officers investigating the fight are now asking anyone who saw what happened to come forward.
The fight happened in the beer garden of Balloon Bar in Bridge Street sometime between 2.30am and 3am on Sunday, March 15.
It involved a number of men and left some of them needing hospital treatment.
Witnesses, or anyone who knows anything about this incident, can call Northamptonshire Police on 101.
Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111 or use the anonymous online form at www.crimestoppers-uk.org.