WILLIAM BEECHING`s previous book, an unauthorized and occasionally frank biography of the Canadian Communist leader Tim Buck, got him and his coauthor Phyllis Clarke into hot water with his comrades. His current book, a memorial to the 1,442 Canadians, himself among them, who fought Franco in the Spanish Civil War, should cause him less trouble. At the time, Canadians split on the merits of a war crudely portrayed as a struggle between Communists and Fascists. Quebec M.P. Maxime Raymond, who later voted against fighting Hitler, claimed good riddance when hundreds of unemployed young Canadians set out for Spain; the Liberal government passed a Foreign Enlistment Act, making them criminals for fighting, as they saw it, for democracy. Despite the law, proportionately more Canadians than Americans ended up in the ranks of the International Brigades. The bulk of Canadian Volunteers Spain 1936-1939 (Canadian Plains Research Centre, 255 pages, $26.00 cloth) is devoted to the dreary, dirty, murderous business of infantry fighting, made worse by inferior weapons, poor training, and the soldier`s perennial nemesis, idiotic orders from the rear. Half the Canadian volunteers died in Spain. Beeching`s style, in keeping with his purpose, is heavy with old-fashioned heroics. Memories, collected from ageing veterans, almost invariably reflect an appropriate pride and sense of achievement. The fashionable distaste for war is missing. Beeching has mined material collected in Ottawa by Mac Reynolds and used by Victor Hoar (now Howard) in a substantial and highly readable book published in 1969. His additions include a comprehensive list of Canadian volunteers and the testimonies of survivors. Apparently no one has yet gone to Spain to discover what more might be found now that democracy has regained what Franco and his Fascist allies stole with tanks and bombs.