The latest installment of the Call of Duty franchise from Activision Blizzard saw a decline of approximately 14 percent in its first month sales on the Xbox 360 and PlayStation 3, according to the latest U.S. retail sales figures from the NPD Group. That includes 4.5 million units of Call of Duty: Black Ops II on the Xbox 360 and 2.9 million on the PlayStation 3, Gamasutra has learned. Figures for the Nintendo Wii U version of Call of Duty: Black Ops II were not available, nor were figures for the portable PlayStation Vita version, Call of Duty: Black Ops Declassified. The publisher had previously announced that Call of Duty: Black Ops II, the Treyarch-developed sequel to 2010's chart-topping Black Ops, had reached over a billion dollars in global sales in its first 15 days on the market. Last year's version, Call of Duty: Modern Warfare 3, sold a record-setting 8.8 million units on Microsoft and Sony's platforms in its debut month, a 10 percent increase over the 8 million units for the original Black Ops in 2010. The launch month for Black Ops II, however, included seven fewer days than did the launch month for Modern Warfare. That difference, 12 days this year versus 19 days last year, was commented upon by Doug Creutz of Cowen and Company in a note earlier this week. Taking that into account, he had expected total units of 7.9 million across all platforms, including the Wii U and handhelds, a decline of 11 percent. Because of the time differential, he cautioned against drawing conclusions about overall Call of Duty sales until the end of 2012. The current split between the Xbox 360 and PlayStation 3 mirrors exactly the split between the two versions for the original Black Ops. In November 2010, the Xbox 360 version sold 4.9 million units in its launch month, while the PlayStation 3 version sold 3.1 million. In both cases, the sequel has seen a modest decline two years later. The possible decline of the Call of Duty franchise has been an important topic this year. Launch-to-date retail sales figures through July of this year showed that Modern Warfare 3 was trailing Black Ops by 2.7 million units in the U.S., marking the latter game as a possible peak for the series. With Black Ops II launch figures down significantly on the two main platforms, it does appear that the original Black Ops will maintain its title as the best-selling Call of Duty game in the U.S.