For a democracy to use violence successfully requires broad acceptance of two ideas that are antithetical to its people in peacetime. One is solidarity between the civilian society and its military services: "Anything for our boys at the front." The other is a concentration on how to destroy the mind of the enemy, with not merely an assault on his resources but with an effort to break his will, through shock, surprise and even terror.

The people of democracies, especially ours, long to avoid these attitudes as long as possible, because their peacetime implications are frightening: the militarization of society, and the brutalization of foreign affairs. That is why the gray world between peace and war is so discomforting. Things get mixed up.

We know we need to maintain military forces that are ready to be used and that therefore must be organized around the principle of effective -- that means mind-destroying -- violence. But we don't like that much, so we keep them caged, at arms length, underpaid, undermaintained and undersupplied. We know -- but often don't admit to ourselves -- that the most effective use of military force is not gradual, slowly escalating pressure, but the sudden destruction of an enemy's strategy: Guderian's blitzkrieg ; Napoleon's 19-th century version of the human sea attack, made possible by the French levee en masse, that shattered -- not merely defeated -- his opponents' 18th-centruy style of warfare.

The operation that failed Thursday night caught the American people in the midst of doubt, but largely still clinging to the hope that they would not have to change their way of thinking -- that events would prove tractable without the need to rely on our military forces or, if it did become necessary, that the force wouldn't really need to be military, that it could be used in a gradual, marginal, slowly escalating, civilian manner. Open up the game theory book, Mr. President, and calmly turn up the pressure -- just don't bother us.

It won't work. All military operations are a matter of calculated risk. Daring and surprising ones put heavy demands on equipment and people, but their very audacity can give them cover and protection. When George Washington launched America's most famous surprise military undertaking, he led an army that, encamped in winter, had lost a third of its members to the cold and a third to desertion. With a part of the third that was left, he made a daring Christmas attack across the partly frozen Delaware, surprised terrorized Hessian troops quartered at Trenton, and gave the revolution its slim chance of life. His men left bloody footprints in the snow.

Sometimes the long shots pay off. Trenton was no less risky than Tehran. When you're driven to the end of your rope, you have to try. But all such long shots are forced -- in spades -- to cope with the inexorble peskiness of wartime operations. If they fail, you have to ask: what next?

The debate will doubtless rage now for some time about the art of helicopter maintenance. Does this failure of a higly prepared mission prove that, even with special care and attention, nothing the military does will work, or that they need more resources to do the job right? This particular failure itself proves neither, but one may hope that the Congres' perennial massive cut of Harold Brown's request for maintenance and operations funds might at least be subject to some second thoughts this year.

We also have to try to understand that, if we must again resort to arms in Iran, or elsewhere, the gradual measured approach is still the most dangerous and has usually proved the least successful. In spite of its failure and the inevitable second-guessing, the recent attempt was audacious enough that it had a chance.