If it had been a group of aliens returning to inspect their handiwork, he would not have stood much of a chance.
Fortunately for Kenneth Wilson the 'trespassers' he confronted were visitors from this planet.
A group of Norwegian crop-circle enthusiasts had come in peace to see the latest 300ft creation in a Wiltshire field.
Mr Wilson, however, was determined to keep any intruders at bay and fired several warning shots at the group, it is alleged.
But his stand was halted by an easily identifiable flying object - a police helicopter.
Dressed in camouflage gear the 62-year-old had set up camp in the middle of the crop circle and armed himself with a shotgun.
When a group of tourists arrived to inspect the design, which is thought to represent a bird with an open beak, he opened fire and shouted at them to get off the land.
One of them, Eva- Marie Brekkesbo, 47, said: 'The gunman was dressed in full camouflage garments, had a black mask over his face and held a gun in his hands.
'When I asked him if he was the farmer, he said that he was engaged by the farmer to prevent anyone from visiting the crop circle.'
She added: 'I have been visiting crop circles for a decade and have in various ways been told that we are not welcome, but this is the first time I have been threatened with a gun.
'Farmers have the right to protect their land, but they have no legal right to threaten people. It was totally unnecessary and incredibly scary.'
A member of the group called the police and with the help of an observation helicopter that was in the area officers swooped in to stop the gunman.
Mr Wilson was arrested at around 2pm on Tuesday. He was later released on bail pending further inquiries.
Repeat offender? A Mayan-themed crop circle, this time in Silbury Hill
But the owner of the field, Richard Oram, claims that he had simply been shooting at pigeons with his brother Sid.
'Sid is ex-firearms,' the farmer said. 'He's always shooting pigeons and rabbits on our farm. He and his brother both had permission to be there.'
Mr Oram that after the circle appeared last Thursday, the disturbed area of land would have attracted plenty of birds to feed on the seeds and insects.
He admitted that crop circles are a problem for him.
'This one alone will have caused £1,000-plus damage,' he said.
Another worker at the farm near Devizes, Wiltshire, described the crop circle as vandalism and said: 'If people go nosing around on other people's land they are trespassing and will be removed.'
Expert Steve Alexander, who spotted the crop circle last week when flying overhead, said: 'I have never encountered anything like this before.
'We know crop circles are man-made and they cause huge problems for farmers because these crops are grown to earn the farmer income. However, there is no justification in using a firearm to intimidate people - that is simply illegal and totally wrong.'
Sid Wilson, 64, refused to comment on his brother's arrest.