SAN JOSE, Calif. – They will march into the predawn darkness, their battle plans carefully researched, meticulously MapQuested and fecklessly flecked with cranberry sauce. If shopping has a national holiday, it is Black Friday, the day after Thanksgiving, when the biggest bargains of the year appear on store shelves.

This assault on the shopping mall is the traditional second act in the American season of excess, which begins with Thanksgiving dinner and the unremitting drone of football. But frightened by a still-stumbling economy, retailers this year have stretched Black Friday to Black November — a monthlong carnival of consumerism that sounds vaguely like a terrorist organization.

“It really has gone from one day over Thanksgiving weekend to a four- or five-week festival of planning and research,” said Brad Wilson, creator of the website BlackFriday2010.com, one of many places shoppers can go online to find “leaked” Black Friday ads for chain stores such as Target, J.C. Penney and Sears.

Last year, Wilson launched BlackFriday2009.com on Nov. 5. “That was plenty early,” he said. “This year, we launched three weeks before that and immediately started getting 40,000 visits a day.”

Wilson’s site also offers shoppers an iPhone app, one of at least half a dozen such mobile maneuvering devices with which consumers can find the latest sale prices this year, maintaining maximum battlefield flexibility.

The leaked ads provide a treasure trove of price information, permitting the most aggressive Black Friday shoppers to plunder the plasma TVs first and end their day easing into a pair of half-off moon boots just as most people are waking up. Target is selling a 46-inch LCD TV for a mere $449; Kohl’s is offering an El Paso Quesadilla maker, listed in stores now for about $20, for $12.99.

“It’s kind of exciting that you can get in five hours of shopping and then go to breakfast,” said Denise Alvord, as she and her 12-year-old son, Gunnar, waited Thursday morning for the Barnes & Noble to open at the Westgate Mall in San Jose. “I think it’s fun to be out there early, and fun to get good deals.”

According to a survey released by American Express this week, 100 percent of American women plan to do some holiday shopping this year, and many of them will be buying big-screen TVs for the terrified 88 percent of men who admit they will not go near the malls until they’ve emptied out again in January. Of the randomly sampled consumers in the survey, 31 percent said they would man the battlements on Black Friday. Or woman them.

“When it comes to holiday shopping, women tend to be a little more proactive about it,” said Mona Hamouly, a spokeswoman for American Express. “They really want to participate.”

Large chain stores such as Macy’s and Kohl’s used to keep their Black Friday prices a closely guarded secret, which is why websites like Wilson’s began cultivating Daniel Ellsberg-type leakers, who smuggled out 40-page newspaper circulars weeks ahead of their Thanksgiving publication date. Wrinkles and smudges on the scanned pages were a testament to the authenticity of the leaking.

But as retailers quickly realized that the leaks helped them move merchandise, they began to leak glossy PDF versions of the ads themselves. J.C. Penney will publish its Black Friday ads on Thanksgiving Day, but the material will be on jcp.com five days earlier.

“We’ve moved our official leaking up by a week,” J.C. Penney spokeswoman Kate Coultas said. “It creates a buzz. Customers are definitely planning their Black Friday strategies earlier.”

Alone among the big chains, Wal-Mart maintains fierce control of its Black Friday pricing plan, and so far no one has managed to pry any early intel loose from the mega-store. (Although rumors of a 50-inch Samsung HDTV at 95 percent off are turning up on the Web.)

But Best Buy, by contrast, has been eager to tip its hand, running Black Friday-type sales every weekend this month. Sears — along with some Wal-Mart, Old Navy, Kmart and Gap stores — plans to be open on Thanksgiving Day, so shoppers can watch the Detroit Lions perform their annual swoon into the mashed potatoes on a wall full of 3-D screens.

Retailers have long recognized the importance of Black Friday — which got its name because it’s the day many stores move into the black of profitability — but it has rarely been the busiest shopping day of the year. That honor usually goes to the Saturday before Christmas, probably because that’s when the men finally come out of hiding.

Black Friday is a day of rejoicing for shopaholics, but the stampedes at “door buster” sales have sometimes led to tragedy. In 2008, an employee at a New York Walmart store was trampled to death when shoppers burst through glass doors before they opened.

With retail sales figures down because of the recession, the importance of Black Friday, by any name, has increased. Wilson expects more shoppers to come out this year, but thinks they’ll spend less. “That’s not a great environment for retailers,” he said. “As they compete with each other to get us to open our wallets, that essentially means a race to the bottom on price.”