And now the arts of peace

''The Falkland Islands are once more under the government desired by their inhabitants.''

Nothing more simply expressed the goal and achievement of Britain's arms than these words by the commander reporting the end of resistance by Argentina. The British forces had been fighting and dying not only for their country but for rights important to all the world - the right to political choice, the right to security from aggression.

Now the task goes on to assure these rights by means other than war. And to restore the international fabric torn in so many ways by the conflict.

Even for such old friends and trading partners as Britain and Argentina, a great deal of patience and goodwill will be needed to overcome the shock of such severe and unexpected combat. Then there are the ties involving Europe, the United States, and a Latin America that by and large accepts Argentina's claims to the Falklands or Islas Malvinas.

The US and European support of Britain's military defense of international law ought to be translated now into no less support of the diplomatic process to bring lasting settlement. US Secretary of State Haig has been among those acknowledging that a military solution would be no solution.

As Britain's staunchest ally, the US has the opportunity to continue encouraging Britain to use victory for conciliation rather than humiliation. With victory so decisive, Britain has the opportunity to prove itself in the arts of peace as it did in the arts of war - not belaboring the unconditional surrender to which it was entitled but joining with its adversary to solve the problem that divides them.

As the major power in the Western Hemisphere, the United States also has the opportunity to take a lead in the healing process there.

Though Argentina was alienated from the US by the latter's eventual tilt toward Britain, it knows that it has a friend in the Reagan administration. Argentina and other Latin American countries could be helped in strengthening hemispheric stability by firm US backing of settlement efforts both bilateral and through the United Nations and Organization of American States.

Meanwhile, Argentina's friends and neighbors would do it a favor by discouraging the fulfillment of threats by some Argentinians to continue armed intrusion in a never-ending battle for the Falklands. This would be no more effective than Argentina's futile full-scale invasion in obtaining a just settlement.

Indeed, a cruel irony of the war is that long-continued negotiations between Britain and Argentina could have been resumed in place of the combat brought on by Argentina's reckless aggression. Apart from being labeled as international lawbreakers, Argentinians must see that the venture was simply not worth it as they count the cost in lives and treasure.

Even in Britain, with the right on its side, the enormous price being paid becomes part of a national debate. The issues concern the magnitude of the military response and the question of whether Argentina could not eventually have been brought into line with international law without all the bloodshed.

A British newspaper sounded a valuable note when it said this was a time to give thanks not only for victory but for each life now saved.

Here is something to build upon.