Decades from now, when a descendant of Ken Burns sets out to tell the definitive story of the 2009-2010 late-night television wars and Shelby Foote's great-grandson narrates monologue jabs over archival photos of disgruntled hosts, those pictures might be more orange than sepia-toned (and they'll be projected holographically on virtual screens just inches from our eyeballs, but that's a tech story).

The last big shot in the battle is likely to be fired Monday night when Conan O'Brien, a former writer for "The Simpsons" who succeeded David Letterman as host of NBC's "Late Night" in 1993 and, temporarily, sat behind Jay Leno's "The Tonight Show" desk, kicks off his new talk show on TBS.

You'll recall that the war began just over a year ago, when Leno, who had been moved to a 9 p.m. weeknight time slot in a disastrous experiment by NBC to make room for "Late Night" host O'Brien (who, six years earlier, had threatened to jump ship unless he got "The Tonight Show"), announced that he wanted his old gig back. Leno's unwatchable 9 p.m. show had proved to be a major embarrassment for the network, which was fielding mounting complaints from its affiliates about the poor lead-in dragging down nightly news ratings.

NBC's solution was to put Leno back on at 10:30 for half an hour, moving "The Tonight Show" back to 11 p.m. and kicking new "Late Show" host Jimmy Fallon into the wee hours. O'Brien's contract guaranteed him "The Tonight Show," but had no language guaranteeing the traditional 10:30 p.m. start time.

O'Brien famously declined via an open letter that began "People of Earth ... " and went on to declare that the time shift would "seriously damage what I consider to be the greatest franchise in the history of broadcasting."

It seemed as if Leno, back behind "The Tonight Show" desk seven months after vacating it, had emerged victorious. But, as it happened, this has panned out to be a war with no casualties — at least so far.

Leno's got "The Tonight Show" back and is using the institution to present his generic, derivative and inexplicably popular shtick. Letterman, delighted, got to sit on the sidelines and stir the pot. Jon Stewart and Stephen Colbert, with their comparatively tiny Comedy Central audiences, have solidified their grip on young audiences as cultural comic pied pipers in O'Brien's absence. And O'Brien himself walked away from NBC with a $47 million severance check and the TBS gig.

There's been scant revelation about the format of his new show, but you've got to imagine that "Conan," as it is simply dubbed, will be more like O'Brien's freewheeling and out-there "Late Night" than his substantially subdued, square-peggish "Tonight Show." Or maybe it will be more like the final week of that show (albeit with a substantially lower basic cable budget), during which O'Brien and company let loose and exhibited a creative fervor audiences of "The Tonight Show" hadn't seen since the heyday of Johnny Carson.

Since cable shows don't need to pull broadcast network-sized crowds, O'Brien will be free to pander to the small but rabid fan base likely to follow him to TBS, a group he has shrewdly maintained his connection with — and perhaps even grown — since his last "Tonight Show" appearance on Jan. 22. Savvy use of social media and the Internet, as well as his live "Legally Prohibited from Being Funny on Television" concert tour which played to sold-out crowds in 30 cities (including Austin) this summer have kept his name in the news.

Fans stepped up, creating their own viral marketing campaigns and purchasing billboards to display O'Brien's Twitter messages. He has used that social media service as well as Facebook, YouTube and even a big orange blimp to promote his Monday return to television. If the show fails, nobody can blame the promotions department at TBS.

Once and future sidekick Andy Richter told the New York Post that the new show will be similar to O'Brien's "Tonight Show," but more relaxed. "This is the first time that Conan and I are starting up a show where we weren't replacing somebody," Richter said. "So there are no footsteps to follow in. It is like our first grown-up party where we don't have to worry about our parents coming home and yelling at us about doing something wrong."

Richter also took some pleasure in Leno's plummeting "Tonight Show" ratings. The Nielsen Co. just reported that Leno's overall audience is down 21 percent compared with 2008, having shed 25 percent of its 18- to 49-year-old viewers. Leno is pulling fewer of those viewers than did O'Brien as host of "The Tonight Show."

"I don't want to wish ill will on anybody, but I would be lying to you if I said it didn't feel a little bit fun to hear that," Richter told the Post. "It is kind of vindicating in a way."