A man was rendered unconscious after an altercation between a group of women in a pub spilled out onto the street.
Police are appealing for witnesses to the large scale disturbance in Boston market place which started in the Stump and Candle pub.
The incident happened at 1.33am on August 27, with police issuing the appeal on the morning of Friday, September 22.
A 39-year-old man has undergone surgery for his serious facial injuries.
Police are currently viewing CCTV from the area but would appeal for any witnesses to come forward.
Anyone with information should contact DC Adams or DS Stafford at Boston CID on 101.
Alternatively, call the independent charity Crimestoppers anonymously on 0800 555 111.