A blockade of northern French ports by French fishermen involved in a dispute with their government has created chaos for British and continental travelers trying to cross the English Channel.

Tens of thousands of people, most of them families heading home from vacation, were stranded in the channel ports over the weekend after French fishermen used their boats and cables strung between them to block cross-channel ferries and other traffic from entering or leaving Dunkirk, Calais, Boulogne, Dieppe, Le Havre and Cherbourg.

In a massive counter-mobilization that is being compared here to the British evacuation of allied troops from Dunkirk during World War II, most cross-channel ferries and hovercraft have been diverted from the French ports to Ostend and Zeebrugge in Belgium to pick up Britain-bound passengers and cars rerouted there.

A few ferries have braved violent head-on confrontation with the fishermen by ramming through the blockade at Dunkirk and Cherbourg, and angry British travelers have clashed wisth the fishermen and other Frenchmen on shore in Cherbourg and Le Havre.

These exploits have been cheered on by the British media and even compared with the victory of the English at the 1415 Battle of Agincourt. British diplomats have conveyed their "deep concern" to have the French government.

The French fishermen are trying to force the government to provide job protection, lower fuel costs and higher price subsidies to help them against cheaper fish imports. They began the blockade last Wednesday at Le Havre, stranding dozens of commercial ships, idling thousands of dockworkers and costing the port more than $1 million a day.

As the blockade spread to Dunkirk on Saturday night, car ferry captain Richard Wilks, a veteran of the Dunkeirk evacuation, steered his 5,000-ton British Rail sealink car ferry out to open water through five fishing boats closing off the harbor. "I was only doing my job," said Wilks, who was an officer on a cargo ship that rescued 600 people from the Dunkirk beaches as the German Army closed in 40 years ago.

While Wilks successfully ran the blockade, French fishermen pelted the hulking vessel with bottles and potatoes, while British passengers threw beer cans back down at them.

This scene was repeated with greater fury in Cherbourg yesterday when the Townsend Thoresen ferry Co.'s Free Enterprise, with "Land of Hope and Glory" blaring over its loudspeakers broke through cables strung by fishermen and withstood a barrage of bolts, wrenches, chains, planks and flares the fishermen fired onto its deck.

When fishermen on the dock tried to prevent the ferry from docking, they were chased away by crowds of British tourists who broke through police lines and helped tie up the Free Enterprise at its berth. Some of the British had been stranded in Cherbourg for more than two days.

In a front-page account of this drama today, Britain's Daily Mail declared that "the spirit of Henry V at Agincourt triumphed again yesterday." The story was studdied with quotes from Shakepeare's "Henry V," including: "And Gentlemen in England, now abed, shall think themselves accursed they were not here . . ."

This evening, the Free Enterprise failed to break back out of Cherbourg harbor while its sister ship, the Viking Valiant tried to force its way into the harbor. They were thwarted by fishing boats and three strands of cable laid across the harbor.