Sometimes an author will opt to dispense with the use of quotation marks for indicating dialogue. Two examples that readily come to mind are Charles Frazier in Cold Mountain and Anthony Burgess in A Dead Man in Deptford.
Use of the initial dash instead of quotation marks is found more often in Europe. Some American and British authors will also adopt the dash to highlight unusual or affected dialect.
In an essay for the October 25-26 weekend edition of The Wall Street Journal, novelist Lionel Shriver lamented the growing practice of dispensing with quotation marks for dialogue in fiction. He attributed this trend to “the broader popular perception that ‘literature’ is pretentious, faddish, vague, eventless, effortful, and suffocatingly interior.”
By forcing the reader to labor in distinguishing speech from narrative–so this theory of the snobbish mindset goes–true literature winnows the many who are called from the few who are chosen.
In historical fiction, however, there can arise a compelling reason to trade quotation marks for the initial dash or to use no marks at all.
The dialogue dash creates a distancing effect that can be particularly effective in historical settings. For example, if you want to portray a character as cold or introspective, the dash choice, or no dialogue marks, can offer an added layer of emotional insulation. Frazier used the dash with fine effect in Cold Mountain to evoke the numbing effect of the Civil War and to mimic a mythic, Homeric tone for his story.
Also, the author who tells a story that alternates between two eras can create a visual and psychological switch by foregoing quotation marks in those chapters that are set in the more distant time period.
But author beware. Many readers abhor the loss of quotation marks. I’ve even read reports of shoppers who have refused to purchase a book because of this choice of technique.