HE REAGAN administration is pulling out all the stops for the first anniversary of the Grenada intervention. That action, in which thousands of fully equipped American military men took a few days to overwhelm a few hundred underarmed defenders, is being hailed as the greatest military triumph since V-J day. Upon this modest operation is being piled a geopolitical weight that would crush the Normandy landing. The event is said to mark a momentous turning point: the United States set aside years of irresolution, showed its regained steel and will, and successfully conducted the first reversal of a communist takeover in history.

To which we say: enough, fellows. The threat to the safety of the American medical students and the apprehensions and appeals of Grenada's neighbors justified the intervention, though it took some weeks for good evidence to come that this was so. Since then, documents have been discovered indicating that Grenada's revolutionaries -- both the winners and losers of the bloody power struggle that precipitated the invasion -- had pervasive communist ties.

Still, a little perspective is in order. The special circumstances of Grenada -- the crisis in the regime, the island's great vulnerability, the democratic cast of its neighbors, the presence of American students -- limit its general significance. A prudent administration would not be pounding the drums if it had something more impressive to show. Anyway, Grenada, though liberated, is far from out of the woods.

By pounding the drums, Reaganites stir suspicions that they seek to draw attention from another event whose first anniversary is taking place, without their calling a lot of attention to it, right now. A year ago -- it all happened just two days before Grenada -- terrorists bombed the Marine barracks in Beirut in the second but, unfortunately, not the last attack on an American facility there.

The political magnetism that attracts the administration to Grenada repels it from Lebanon, scene of a succession of military disasters and a parallel series of political frustrations. These include the failure, after helping remove most PLO forces, to ensure the safety of Palestinian civilians, the failure to put Lebanon back together again, the failure to make the Israeli withdrawal agreement stick and the failure to pry out the Syrians.

We continue to think the Reagan administration had good initial reason -- to protect civilians, to steady the Lebanese -- to put Marines ashore in Lebanon. But there is no denying, unless you are working directly for the president's reelection, that the results were bitter. To laud a relatively easy, successful intervention and black out a heartbreak intervention is to distort reality and to miss learning the lessons that must be drawn.