Lee Hollingsworth and Alex Walster were among a group of five who carried out the night time assault in Silver Street in the town.
Sarah Lloyd, prosecuting, said the two men had been drinking for over 12 hours celebrating Hollingsworth’s birthday, ending up at the White Horse pub.
Hollingsworth became involved in an incident on the dance floor with Jamie George and was asked to leave by door staff.
Mr George and his friends Jade Henry and Carl Pearson stayed in the pub before leaving just before 11pm.
As the group made their way through the town centre they were confronted by Hollingsworth who suddenly began punching Mr Pearson. The blows knocked his victim to the floor where he was subjected to further blows and kicks.
Mr George was also knocked to the ground and attacked.
Hollingsworth and Walster were joined in the violence by two other friends.
Meanwhile Jade Henry was assaulted by Hollingsworth’s girlfriend Nikki Booth.
Booth ripped out Ms Henry’s hair extensions and repeatedly struck her, forcing her to the ground.
The incident ended with both Mr Pearson and Mr George being kicked as they lay unconscious and defenceless on the ground.
The entire incident was caught on CCTV, and the operators alerted police to the violence. The attackers were then arrested as they made their way from the scene.
Mr Pearson suffered two black eyes, facial swelling and bruises. He declined hospital treatment on the night but collapsed at home 48 hours later and was taken to hospital.
Mr George also suffered a black eye and bruising while Ms Henry suffered bruising and swelling as well as pain from having her hair pulled.
Hollingsworth, 22, of Waterworks Street, Gainsborough; and Walster, 24, of Andover Close, Lincoln; each admitted affray and two charges of assault occasioning actual bodily harm. They were each jailed for nine months.
Nikki Booth, 22, of Waterworks Street, Gainsborough; Mihkel Niit, 23, of Ashcroft Road, Gainsborough; and Shane Essom, 20, of Noel Street, Gainsborough; each admitted affray and one charge of assault occasioning actual bodily harm. They were each given a four month jail sentence suspended for two years and 120 hours of unpaid work.
Sunil Khanna, for Hollingsworth, said he had been drinking from 9am and could not recall anything of the incident.
“His last recollection was about 8pm. The next thing he remembers is waking up in the police station.”
“He accepts the way he behaved was appalling and he is disgusted by what he has done.”
Mr Khanna said Niit had not been with the others during the day as he was working. He became involved after bumping into his friends after they left the White Horse.
Mark Watson, for Walster, said he was disappointed in himself for getting involved.
He said Walster has not been back to Gainsborough since the incident and plans to start a new life in Northern Ireland with his pregnant partner.
Mr Watson said Essom only became involved at the end of the violence and has since shown remorse.
Joanne Staples, for Booth, said she acted out of a misplaced sense of duty towards her boyfriend, Hollingsworth. She described Booth as a vulnerable young woman who suffers from depression.