The battle between Ulster's embittered factions is reaching across the Atlantic to the increasingly important propaganda platform of North America. Successive Irish politicians and protagonists have found in the past that putting their case to the American people has brought much-needed support in the form of funds, manpower, and even weapons.
Now Ulster Loyalists (Protestants loyal to Britain), feeling that Irish republicans have held the American stage almost unchecked for far too long, have launched a campaign of their own.
The Rev. Ian Paisley's thwarted tour of the US is only the latest in a series of moves by Ulster's Protestants to garner American support. The Protestant hardliner was refused a visa by the US because of the ''divisiveness'' of his ''actions and statements.'' (Last week Ulster police arrested several men for operating illegal roadblocks, presumably part of Mr. Paisley's ''third force'' paramilitary organization.)
This year, for example, two Protestant church delegations (Anglicans and Presbyterians) have made lengthy visits to the United States to put forward the Protestant case. They also wanted to show that Ulster Protestants are not all red-necked backwoodsmen and bigots.
Then, in the autumn, the State Department sponsored a 30-day visit to the US by three leading Ulster politicians to present the more moderate point of view. Two were Roman Catholic and one Protestant.
Mr. Paisley had planned to join two other Unionist politicians, John Taylor (a member of the European Parliament) and Peter Robinson (a member of the British Parliament), for a two-week tour in January to help put the Loyalist cause to the American people. The Unionist tour, labeled ''Operation USA,'' will go on without Mr. Paisley. Besides the other two MPs, it will include Mrs. Norah Bradford - wife of the Rev. Robert Bradford, the MP who was murdered by the illegal Irish Republican Army in November.
Mr. Paisley, as ever undaunted, plans to visit Canada at the same time. His proposed tour of the American southern states will be undertaken by the other two Loyalist politicians.
Successive American administrations have had to face much the same problem with the Irish question. During the Irish War of Independence, from 1916-1922, Eamon de Valera, an American citizen who became a front-line fighter and later the dominant founder-figure of the new Irish Republic, went back to America for a period to canvass support.
At the beginning of the present Ulster troubles, Joe Cahill, an IRA veteran sentenced to death for his part in killing a policeman in 1942 and later reprieved, played a prominent role. In 1971 he tried to enter America to raise funds, but was barred from doing so.
Fund-raising is an important part of the Ulster struggle, particularly on the Republican side. Noraid, a group described by US and Irish officials as the best organized and most fervent ally in the US of the IRA, has raised large sums for republicanism.
Although the organization claims that this money is used for humanitarian purposes in Northern Ireland, the security forces point to a considerable traffic of arms to Ulster from across the Atlantic and the Eastern bloc.
And arms cost money. This year alone, in the wake of the IRA hunger-strikes, Noraid raised $250,000 in the six months from February. And this is a conservative estimate.
Any solution will take a very long time. Meanwhile, moderate Unionists here feel that much needs to be done to present their case internationally and that ''Operation USA'' may have some merit.
On the other hand, they wonder whether the spectacle of Mr. Paisley on the stump - even in Canada, where he is bound to create headlines - is not the best way to win friends and to influence people.