Visitors to the annual Appleby Horse Fair in Cumbria have been warned police will take a "zero tolerance approach" to violent disorder.
Cumbria Police said it would be focusing on the possession of weapons after a large number were seized at last year's event.
Latest police estimates suggest up to 50,000 people are expected to attend the week-long event.
Last year a number of bladed weapons and ball bearing (BB) guns were seized.
Thousands of travellers and gypsies, many in traditional horse-drawn caravans, have already arrived for the fair, which begins on 3 June.
Cumbria's assistant chief constable, Jerry Graham, said: "At last year's fair, a high number of weapons were seized.
"If anyone is found in possession of a weapon or plans to cause violence and disorder then their fair will be over.
"They will be arrested and face the prospect of being banned from the event or spending the fair in police custody.
"We will deal with offences proportionately and robustly to ensure that everybody can enjoy the fair safely."
Visitors have also been warned that items that could be used as weapons, including baseball bats and whips, will not be allowed to be carried in public without a "valid purpose".