The gloomy world of Bertolt Brecht's Mother Courage and Her Children is as unremittingly awful as that of Samuel Beckett's plays, and it is illuminated and relieved by very much the same kind of mordant wit, and a pretty similar kind of gritty and indomitable (and perhaps foolhardy) survivalism. You can't call it a determination to survive: it's not as though Mother Courage actually had a choice in the matter. Rather, like many of Beckett's characters, she might say, "I can't go on. I'll go on."

In most obvious ways the two styles of drama are at opposite ends of some kind of artistic spectrum (this is especially true in the case of the ART's spectacularly and aggressively theatrical mounting of Brecht's show at the Loeb Theatre Centre in Boston). But they pose a similar kind of challenge, in that either can easily fall off one side or the other of a knife edge between wallowing in gloom on the one hand and overplaying the gallows humor into triviality on the other.

János Szász's masterful production (based on an earlier one he did in Hungary) tramples over the dilemma by overwhelming us with sheer theatricality. The considerable resources of the Loeb are used to generate a whirlwind of powerful images and events which sweeps both laughter and despair before it: you leave the theatre not quite sure what to feel, more shell-shocked than moved.

When you walk into the theatre there's an authentic train track running from the stage up the center aisle to the main cross-aisle. As the show starts, everything goes black, and there is an astounding, deafening bass growl from the sound system (maybe the voice of War, I don't know -- it turned out, as it continued, to be something rather like an amplified version of those Tibetan monks who sing in that strange deep extended burp). Gradually, out of the orchestra pit, right in front of us, heads rise in to view, eventually becoming full standing figures, perhaps a score of them, half on each side of the strangely ominous railroad track. Some of the heads, we discover as the platform continues up, belong to life-size replicas of the terracotta emperor's soldiers excavated in China; others are the actors, standing among them. It takes a minute to see that some of the motionless figures are real. One, it turns out, is a boy playing the young Brecht (acting as our narrator) who steps over onto the track to start   the play.

Like any good Brecht production, this one lays the mechanics of theatre out before us, making no attempt to conceal the workings of the show, to hide the fact that this company has come together to tell us a story, not to fool us into thinking we're witnessing an event. Or, put it another way: the event we're witnessing at any given moment isn't Mother Courage surviving the Thirty Years' War by whatever means come to hand: it's Szász and the American Repertory Theatre telling us about her, and about the nature of War.

Besides the terracotta soldiers, who play a recurrent role in telling us about the inhumanity of the way War converts people into disposable objects, the most striking device in this production is a huge rusted-metal structure, three stories high and perhaps thirty feet wide, which is wheeled around into various positions by the crew, occasionally assisted by members of the company. One side of it is a huge corrugated metal wall, leaning back away from us, pierced by seven or eight irregular holes which might be bombed out windows. As it moves toward the audience, it feels like a representation of some huge, implacable institution, perhaps War itself, particularly when, as it does a couple of times, it sweeps the dead and dying into the suddenly receptive mass grave of the orchestra pit, where they disappear.

The other side of this mammoth object, revealed as it turns, is a series of openwork metal platforms, with a gigantic ladder running up the center, rather like the inside of the ruined building. From the opening scene, this gigantic shape dominates the action, dwarfing the actors who swarm up and down it, making it, as needed, into a fortress, a ruin, a wall, whatever's necessary. A second structure, equally tall but more openly constructed, was swung into view as needed.

Almost equally odd, though arguably less effective, is Mother Courage's cart, which Szász chooses to make into a sort of caravan of baby carriages and prams, varying in length and elegance according to the relative prosperity of the military supply business she and her children run, following the soldiers and selling boots and brandy. While the symbolism of this is obviously appropriate, it might be argued that it is too much so, as at the end Mother Courage loads her dead children into the remaining three carriages. On the other hand, subtlety is not the first word that would leap to your lips as you searched for a way to describe this overwhelming experience.

In a way, the star of the show -- as is appropriate for Brecht's view of what theatre is and how it works, and as was also the case in last spring' s Full Circle -- is the twenty member company, who swirl around the stage, and up and down the daunting structures and through the audience in a continuous, tightly choreographed vortex, pulling us into the nightmare world of the never-ending Thirty Years' War.

There are major roles, however much Brecht would probably have liked to get along without them. Jonathon Roberts as Eilif, Mother Courage's first son, who is lured off to join the army by promises of glory and becomes a war criminal in a way poignantly recognizable against the background of the last decade's news from the Balkans, is strong and pathetic. Her second son, Swiss Cheese, is a more demanding role both physically and in terms of range, and Tim Kang brings us to feel sympathy for his equally am bivalent and irrational need to do his duty and save the Second Regiment's cash box, an absurdity for which he winds up paying with his life -- in this production in a surreal combination of crucifixion on the metal wall and firing squad.

Mirjana Jokovic (who was an admirable Dulle Griet in Full Circle) is astonishing as Mother Courage's mute daughter Kattrin, using her body and the occasional inarticulate cry in remarkably effective ways to make her the most sympathetic and admirable figure in the play. But the real star turn in this show is Karen MacDonald, whose Mother Courage achieves the powerful, vibrant and indomitable figure the script requires. Having seen her picture in the program and t he lobby display, I could hardly believe she could transform herself into the stocky, stolid, defiant and gloriously homely figure, contorting her face into a powerful mask of agony as, at the end of the first act, she denies knowing Swiss Cheese, aware that his body is to be thrown in a ditch as unidentified.

There are other memorable figures -- Thomas Derrah plays a wonderful ineffectual, dogged chaplain, and John Douglas Thompson is a startlingly sympathetic and yet contemptible general's cook. One of the peculiar aspects of the experience of this production -- and one that's not inconsistent with Brecht's ideas about how theatre ought to work -- is that in some ways the story invites a kind of soft-headed, cheap sentimentality. Over and over, we see terrible things happen to people we've just been manipulated into caring about, and the manipulation is so obvious that we don't quite know how to care. There's a wonderful sequence near the end, for instance, when Kattrin -- with nothing much left to live for -- warns a village about to be attacked by a group of soldiers by banging deafeningly on the metal beams of the second structure, climbing to the very top, her metal bar clanging all the way and the theatre's sound system chiming in. As she arrives at the top, one of soldiers shoots her and, in the darkness, she apparently falls the 25 feet or so to the railroad track; we hear the sickening thud of her body and the clang of her metal bar, and, as the soldiers run off, their surprise attack aborted, here comes MacDonald's Mother Courage, alone now pulling her baby carriages, to find Kattrin's body.

On the one hand, it's a powerfully affecting moment; on the other, we don't know how to be affected, as Mother Courage loads the dead Kattrin into a baby carriage and starts over to where, we suddenly discover, the bodies of Swiss Cheese and Eilif are waiting for her. The grotesque irony of her continuing to bear the weight of her children, to bear as well her guilt for her part in their deaths, is so over the top that mere human sympathy seems beside the point. Perhaps that's the essence of tragedy.

In the end everyone -- except possibly Mother Courage herself -- is dominated and swept along by the war itself, their lives shaped by the whirlwind which, though it can be started by human action, can't, once launched, be controlled. What's most ironic is that it's Mother Courage's very strength, her ability actually to do something about her situation, that makes her responsible for the deaths of her children. Everybody else is simply swept along. Her situation is worse because she's retained some semblance of responsibility, making bad and good decisions, but making them, and ending with her dead children in the baby carriages, struggling off into history, screaming "Peace be with you!" Indeed.