Gamers have enthusiastically answered Activision Blizzard’s “Call of Duty,” as the publisher celebrated Veterans Day with a victory as its military videogame became the biggest entertainment launch in history.

That record already belonged to the industry’s biggest gamemaker when Activision’s “Call of Duty: Modern Warfare 2” stormed into stores last November.

For the second year running, the franchise has broken entertainment industry opening day records, with sales of “Call of Duty: Black Ops” hitting $360 million in the first 24 hours in the U.S. and U.K. All totaled, the company said players bought some 5.6 million copies of the game. Five million gamers alone were playing the title online in its first hours of release on Tuesday.

It’s an encouraging start for “Black Ops” — which blew past last year’s “Call of Duty: Modern Warfare 2” opening day sales by 16%. That title went on to record sales of $550 million in its first five days and $1 billion over the 2009 holiday season.

The numbers illustrate the drawing power of the games biz, as other entertainment stalwarts have not come close to the first-day sales for “Black Ops.” It certainly dwarfs the top film opening, which belongs to Warner Bros.’ “Harry Potter and the Half-Blood Prince” with $394 million earned over three days.

Publicly, Activision has said it does not expect this year’s installment of the series to perform quite as well as “Modern Warfare 2.” Industry analysts, though, think the company is taking a deliberately conservative stance for investors and actually has quite high internal expectations.

“There has never been another entertainment franchise that has set opening day records for two consecutive years and we are on track to outperform last year’s five-day global sales record of $550 million,” said Activision CEO Bobby Kotick in a statement.

The performance is a vindication for Activision and developer Treyarch, as many gamers and industry observers were doubtful earlier this year that the company would be able to match the quality or sales of “Modern Warfare 2,” produced by Activision’s Infinity Ward studio.

Infinity Ward and Treyarch take turns producing the game year by year and many saw this edition as a pivotal one for the series. That’s chiefly because of the abrupt February firings of Infinity Ward heads Jason West and Vince Zampella, who created the franchise and produced “Modern Warfare 2.” A series of particularly ugly lawsuits between the parties soon followed.

But consumers were unfazed. “This isn’t a situation where it’s a company employing children making shoes in Indonesia,” said Colin Sebastian of Lazard Capital Markets. “It’s about executives asking for millions of dollars. I don’t know if there’s any sympathy for Infinity Ward in terms of the mass market.”

The real test for the game, of course, will come with sales over the next two months, as the initial rush wears off and traditional retail patterns take hold. “Modern Warfare 2” remained among the industry’s Top 10 selling titles for most of this year. That’s a rare accomplishment in the fast-changing world of videogame sales.

Activision plans to release several digital downloaded add-on packs, a strategy that has kept players engaged well beyond their initial time with the game and has actually impacted overall industry software retail sales this year. “Modern Warfare 2” players were so busy playing the game long after its release that they weren’t buying newer titles.

“The tail of these products is getting fatter and that’s because we’re getting better at providing additional content and services following those large retail releases,” said Thomas Tippl, Activision’s chief operating officer, said in earnings call last week. “I would not be surprised (if) ‘Black Ops’ follow-on revenue … sets a new record in terms of percentage of total revenues for the franchise.”

(Marc Graser contributed to this report).