At one of W. Germany's finest theaters: biting politics, bracing drama

In a pleasant town in the Ruhr Valley, an ancient German hero prowls the stage, masterminding his victory over the Roman legions of Augustus. His raincoat is modern, and - more surprising - his beret looks as if it came from the very shop that used to supply the late Che Guevara with his headgear.

The resemblance is not accidental. By their hats you shall know them.

The town is Bochum, and its theater is generally considered to be one of the finest in West Germany - second only to Peter Stein's Schaubuhne in West Berlin.

It is run by Claus Peymann, whose specialties are spectacle, grotesque humor, and leftist politics. Dismissed from his previous post at Stuttgart for paying the dental bill of an imprisoned terrorist, he moved on to Bochum, an agreeable center of modest shops, which also serves as a dormitory town for automobile workers in the Ruhr Valley. Peymann has just been named director of the Vienna Burgtheater in 1986.

The theatergoers of Bochum get both the classics (especially lots of Goethe and Shakespeare) and contemporary works, including usually the first look at new plays by two of the leading dramatists of the German-speaking world - the Austrian Thomas Bernhard and the East German Heiner Muller.

Curiously, Peymann's productions of classics are likely to be more frankly political than his contemporary plays. Consider the present revival of Heinrich von Kleist's ''Hermann's Battle,'' which has been acclaimed in West Berlin, Paris, and other theater centers.

It was a political play when Kleist wrote it in 1809 - not just a quaint historical record of the destruction of the Roman Army in the Teutoburg Forest in AD 9. Kleist thought of the Emperor Augustus as the equivalent of a contemporary predator, the Emperor Napoleon, who, he thought, should encounter equally effective resistance from the Austrian and German princes of the day.

Kleist found in Hermann - the leader of the Germans in the first years of the Christian era - the perfect model of the unscrupulous champion of a good cause, perhaps a little like Machiavelli's Prince. He pretends to be the Roman's friend , even permits his wife to conduct a flirtation with the Roman legate, but then turns on the Romans and helps his allies to destroy them.

Over the years, this play, the only one by Kleist to be unavailable in English, has been made to express the German nationalism of each passing era. As Peymann's program reminds us, an East German version in 1957 made the Americans the modern equivalent of the imperialist Romans. (Peymann's programs are extraordinary. Both in Stuttgart and in Bochum he has supplied a text of each play and thereby made himself the leading publisher of plays in the German world.)

In the present production, the diversity of costumes make the play timeless. At peace, the Romans are dressed like Napoleonic or colonialist soldiers of Kleist's time, but in battle they look more like modern combat troops. Germanic leaders like to wear horned helmets suited to Hermann's time, but Hermann prefers his Che beret, and that fits the general impression. The genteel Romans, proudly bearing the white man's burden, find themselves among a savage race whom they are civilizing. In the program an American scholar underlines the point by testifying to Kleist's interest in the Napoleonic colonial activities in Haiti, thereby providing a convenient allusion to America's Caribbean adventures.

The basic political comment is clear - the Romans are Napoleon's Frenchmen and also the imperialists of today. Once this message is clear, Peymann can go on to have fun, as he notably does in the episode in which the flirtatious Roman legate gets his deserved punishment.

The legate's manner is extremely artificial and excessively sissified, as if he is giving the beastly Germans an exceptionally good lesson in how to behave. He has a rendezvous with Hermann's wife, the fair Thusnelda, at a stylized moonlit garden.

But she has led him to a trap: She locks the garden gate, and complains pathetically all the while he is crushed by a bear. There is German savagery for him!

But the battle is the payoff. The Romans, in a phalanx of oversized shields, march vainly, sliding and slipping through a chaos of thunder, lightning, rain, and mess.

Acclaimed as king of the Germans, Hermann stands triumphant; the shadow he casts grows larger and larger till the lights go out.