Farmer Stuart Johnstone, 46, arrived at his rented land in Baxter Wood to find his sheep nervous and distressed in a neighbouring field, the court was told on Friday.
Seeing Matthew Whitaker with two labradors, one off the lead, Johnstone challenged him, punching him once in the face.
Mr, Whitaker, who was left with reddening to his left cheek, took a picture of Johnstone and told him he would be reporting him to the police.
He later told police he had checked the field for livestock before crossing on the public footpath and keeping his younger dog on a lead.
Johnstone had shouted at him, telling him to get his dog on a lead, there had been a confrontation at a stile and the farmer had hit him.
Johnstone, who admitted assault by beating, had his main farmland in Colne, but rented additional land in Cross Hills.
The court heard he had suffered in the past from rubbish being left in the field and on the afternoon of December 14 had received a call telling him that there was a black spaniel dog running loose.
In mitigation, John Mewies said when Johnstone had arrived, all 137 of his sheep had gone from the field, a wall had been knocked down and they were all on neighbouring land.
“Thankfully, there was no injury to the sheep, but he could see they were all traumatised and cowering in a corner of the neighbour’s field,” said Mr Mewies.
Mr Mewies said although Mr Whitaker’s dogs had not been responsible and there was no excuse for Johnstone’s behaviour, he asked magistrates to put themselves in his position.
He said the footpath over the land had been such a constant source of trouble for Johnstone that he no longer rented the field.
“The public opinion is that it is a public space and there is no regard for farmers or their stock. In the winter it is used as general recreation ground for children and their sledges and all sorts of rubbish is left there,” said Mr Mewies.
Johnstone – who, Mr Mewies admitted, had a bit of a temper – had registered complaints with the police and had called for dogs to be kept under control but had received a “less than charitable” response.
Mr Mewies said Mr Whitaker had simply been in the wrong place at the wrong time and as a result had suffered a slight injury.
“My client has given up tenancy of these acres and the owner cannot lease it out because of the problems and it will now fall into disrepair,” he said. “He is glad that he has no reason to go to Cross Hills.”
Magistrates told Johnstone, of Skipton Old Road, Colne, that they had some sympathy for his situation, but that he had admitted assault. He was fined £40 and was ordered to pay £100 compensation to Mr Whitaker, a £20 victims surcharge and £85 costs.