A single punch delivered resulted in the death of a 35-year-old man who was a stalwart of the county's Hindu community.
Yesterday at Leicester Crown Court Liam Dann, 23, admitted Sachine Popat's manslaughter, having assaulted him outside Molly's bar in Northampton town centre on August 30.
About 1,000 people from Hindu communities across the county attended a prayer session at Wellingborough's Hindu Community Centre following Mr Popat's death.
Dann, of Rookery Lane, Spring Park, Northampton, was jailed for 42 months by Judge John Milmo.
Christopher Donnellan, prosecuting, said: "Mr Popat was attacked by this defendant. It was unprovoked and totally unexpected.
"The defendant struck him on the lower part of his face with his fist and the blow struck him totally by surprise.
"Either dazed or knocked out by the blow, his head hit the ground, causing head injuries from which he died a short while later.
"The motive is not known but it may have been a fit of aggressive jealousy for something his girlfriend said to him before the blow was struck."
Mr Donnellan said Mr Popat, of Colwyn Road, Northampton, had been struck by a single punch "with moderate force".
Passing sentence, Judge Milmo said: "I accept you did not intend either to kill or cause Sachine really serious injury. Had you these intentions, you would have been charged with murder.
"But the sooner people realise a punch to the jaw or face, causing a victim to fall to the ground, may cause the victim's head to impact on a solid surface, whether it be the floor of a public house or the edge of a pavement and that may and often does cause a fracture to the skull, brain haemorrhage and death from head injuries."
Mr Popat was a sales representative who devoted his spare time to helping others.
He regularly attended Wellingborough Hindu Community Centre and nearby Hindu temple.