The instant you glimpse Anne Bancroft as Golda Meir on Baltimore's Mechanic Theatre stage, you are aware that this will be a exceptionally deep actress at her best. Unfortunately, William Gibson's play is concerned as much with the Yom Kippur War of 1973 as it is with his flity heroine.

Gibson's absorption in the war is understandable, since it ended Golda's career as prime minister of Israel. But he forgets that there is nothing more boring to watch than monosyllabic military officers gathered around a table discussing maps once cannot see.

The playwright's decision to tell Golda's story within the framework of the year is defensible, if risky, for it puts her in perspective. But the dramatic line wavers in his multi-scened, two-act drama. There is too much for us to take in about the Syrian border, the Soviet threats, exchanges with Moshe Dayan, phone calls to Ambassador Dinitz in Washington, his reports on what Nixon said, what Kissinger said, about Phantom jets being on their way to Israel or not being on their way to Israel.

The problem is reflected in the unclear, even equivocal, portrait of one of the play's major figures, Dayan, who, on the day "Golda" opened was himself discussing virtually the same questions in the Carter White House. In other words, the story of Israel's survival is not yet over, and that makes for an inherent risk.

One never questions the truthfulness of Gibson's approach: that while the '73 war tipped and turned, Golda's own thoughts would return to her past, her father's reaction to pogroms i their native Russia, her girlhood memories of Milwaukee, her youthful involvement with politics in Denver, her bitter realization that she had sacrificed husband and family to her concern for the Promised Land.

Newsreels, photos and sounds tracks are used in the memory process, though sometimes we hear phoned conversations and at other times do not. Briefs scenes do enrich the character mosaic, but at the price of sustained scenes. The longer scenes - Her parting with her husband, and a scene in a TV studio in which the wise old lady wants less lighting so that sweat will not be misinterpreted as fears - have a meaningful rise and fall which involves us more than brief or repetitive ones.

Throughout, Bancroft sustains the strong, aging figure of scene one, where Golda rises from sleep to pick up the phone and learn of enemy attack. The face is lined and heavy, large nose, dark eyebrows and a sagging chin. The body moves slowly, the back hunched, the legs swollen with time's infirmities. The voice is in low register, strong, gruff, scrappy.

There is also Meir's cigarette addiction.

Bancroft has more to offer than such technical mastery. She is aware what Meir's vision for a nation has done to ther personal life. It is in the sustained scenes that this comes through most movingly, an already vivid portrait which repetition unquestionably will enrich.

Arthur Penn's production has a commanding, assured flow and in the supporting cast of 25, Gerald Hiken's husband; Ben Hammer's Dayan and Vivian Nathan's Lou have particular clarity. For the most part, the others double as as scores of characters. More sustained scenes and less accent on the details of war could provide a less distracting, more absorbing play.

"Golda" returns the Theater Guild to active production, its 229th since its founding in 1919, a first-class, honorable reentry. The Baltimore run is through Oct. 8.