Innovative filmmaking, strong reviews and a strategic ground campaign in theaters has helped a documentary film about World War I win some box-office glory among big-budget blockbusters and Oscars contenders.

“They Shall Not Grow Old” was made with archival film footage, which director Peter Jackson (“The Lord of the Rings”) restored, colorized and transformed with 3-D techniques. It hit theaters in stages, beginning in December with a series of one-night showings around North America, a release method more common for live operas, concert films and rereleased classics like “The Wizard of Oz.”

By the third of those weekday showings, in January, the R-rated “They Shall Not Grow Old” had grossed $8.3 million, breaking the box-office record for such “event cinema” releases.

“We got many, not a few, emails from prospective customers who wanted to get in but the movie was sold out. We just don’t hear from audience members like that,” says Jeff Goldstein, president of domestic distribution for Warner Bros. Pictures.