Old-fashioned tale of war brides; War Brides, by Lois Battle. New York: St. Martin's Press. 359 pp. $13.95.

There is a long tradition, exemplified by Ruth and Pocahontas, of women marrying men whose homes are far away in foreign lands. No class of women has ever been exempt: Royal princesses, often little more than children, were married off to heirs-apparent in far off courts; and as the new countries opened up, many women, usually orphans, were sent out to marry men they had never seen in places they knew nothing about. Lois Battle's novel, ''War Brides,'' gives the theme a more contemporary aspect. It is concerned with women who in wartime marry men they hardly know and who then, in peacetime, rejoin them many thousands of miles from home.

Battle's war brides are three Australian women who marry American GIs, whom they meet while the men are on leave in Australia. When the war ends the women sail to the United States with varying expectations of the men they have married , the lives they will lead, and the country which they know only from Hollywood movies.

Sheila, the youngest, married because she was very much in love with the handsome, much-decorated but somewhat inarticulate Billy, and because she is determined to get as far away from home as possible. All she really knew about Billy was that he came from Virginia. Dawn, a widow with a young child, married Zac because she was a gentle and loving woman who missed the habits and customs of married life. And the elegant Gaynor married the eligible Ricky Cunningham because his wealthy family promised her escape from her disreputable mother and an outlet for her considerable ambitions.

Nothing, predictably, turns out to be quite as expected. Sheila's imagined Virginia plantation turns out to be a shack in the hills with no indoor plumbing. Dawn's dreams of cozy domesticity are confounded by a series of moves and lengthy separations, as her husband stays on in the Navy. And Gaynor's husband wants to be a professor of literature and sever all connection with his wealthy and hated father.

The women react in varying ways to these changes and to their husbands' own expectations, which have been as little founded on reality as those of the women they married.

It is in many ways an old-fashioned book by current standards, because virtue , perseverance, and love are rewarded, while those who deserve it get their comeuppance. It is not a profound book, and one suspects that Battle had no wider ambition than to tell a story, but it is a pity that she didn't explore more of the contrast in custom and countryside. Her Australia is a place of voices, though she does have all the appropriate colloquialisms, but not of landscape, and the sense of being foreign, of having divided loyalties, is too lightly glossed over. Battle has made a valiant attempt to describe the real difficulties of living up to Ruth's brave words ''Where thou lodgest, I will lodge. Thy people shall be my people,'' but it is not quite enough. Imagine, though, what a tale Pocahontas could have told.