World War II memoir -- coming of age in the trenches; And No Birds Sang, by Farley Mowat. Boston: Little, Brown & Co. $10.95.

Farley Mowat, the Canadian adventurer best known for his forays into the bleak northern wastes and his confrontations with Arctic wolves, has presented us with a memoir of his biggest adventure of all, World War II. It is a sad story, and the only wolves are of the human variety.

All soldiering may be divided into three stages -- preparation, action, and (for the fortunate) survival and assessment. Now, long after the last bullet, Mowat is ready for his assessment, and it is a chastening indictment he offers of war and his own loss of innocence.

One of the book's charms is Mowat's ability to re-create and poke fun at his own youthful romantic posturing. Nicknamed "Squib" for his diminutive stature and boundless energy, Mowat is as eager to go to war as a Boy Scout about to set out on his first camping trip. Like Henry Fleming in Stephen Crane's "REd Badge of Courage," "Squib" Mowat has a head full of dreams and heroic notions. At firts, even the elements conspire; his practice soldiering takes place on a field fit for Gothic romance -- "a waste of blasted health overgrown with thorny gorse." As he writes to a girl, he "can't wait for the show to open."

And the "show" opens well. Mowat and his fellow "Hasty Pees" of the 1st Canadian Infantry Division take part in the successful Allied invasion of Sicily and Italy. The Canadians meet light resistance, and the feeling is one of a lark -- as if the boys are taking part in a slightly more serious football game.

But suddenly, south of Rome and amid the mountains, the Germans stiffen, the fighting turns savage, and the scenes of war become uglier and more bestial. Mowat watches helplessly as a German rifleman senselessly shoots up a donkey; as a man is cut in half, eviscerated by a shell fragment; as a good friend is chopped down in a hail of bullets. He is himself saved, fortuitously, when cans of bully beef in his pack deflect the Schmeisser bullets. Suddenly fear (the Worm That Never dies, as Mowat calls it) takes over, and the book clunks to a precipitate ending in 1944 -- long before the war's end, Farley Mowat's private war is over.

At the end, "Squib," that energetic and charming youth, is emotionally dead, like Keats's knight-at-arms "palely loitering" and at a great moral distance from those back home, who cannot understand.

One recognizes the pattern -- innocence and disillusionment, the hard lessons; and in this sense we have encountered a similar message in the work of Hemingway, Erich Maria Remarque, the English poets of the Great War. But the pieces of Mowat's puzzle, his war, are fresh and full of discernment.

For example, he catches the peculiar sang-froid of a British brigadier instructing officers: "Can't let the Hun Spend the rest of the winted there all nice and comfy-cozy. . . . Our chaps over here will smash across the Sangro and gallop up the coast to Pescara, then make a left hook into the mountains and pounce on Rome from the east."

Of course, they are able to do no such thing. The Allies slog through in bitter fighting, leaving bodies behind them like mile markers in what rapidly becomes a terrible war of attrition.

In what he calls an "anti-epilogue," Mowat confesses he has written "in the absolute conviction that there never can be a 'good' or worthwhile war." Like Wilfred Owen, Mowat intends to expose the Old Lie; and this is a worthwhile addition to the shelf of protest literature, which continues to EXpand as long as we have the felt memory of past wars and the prospect, however unfortunate, of future conflicts. Yet antiwar books, even good ones like this, remind us that, if peace ever were once and for all, there would not be need for one more antiwar book.