In 1778, France supported the U.S. in its war against King George III. This week, French advertising group Publicis and U.S. firm Omnicom announced a merger, a move that will effectively dethrone Britain’s WPP as the world’s largest communications group.

John Wren, head of Omnicom and Maurice Levy, chairman and CEO of Publicis, announced the impending merger at a Paris press conference. The new supercompany will control nearly 40% of the American advertising industry, putting it in questionable territory regarding antitrust legislation.

Levy will eventually become chairman of the new Publicis Omnicom and Wren will take over as CEO.

WPP’s Sir Martin Sorrell expressed his speculation about the ability of Publicis to continue to lead in the digital space, as it had been growing by acquisition of small, digitally-savvy organisations. The merger with Omnicom, though a potential boon to both companies, may present challenges to Publicis Omnicom when operating in the fast-moving digital communications space.

Levy says, “The communication and marketing landscape has undergone dramatic changes in recent years including the exponential development of new media giants, the explosion of big data, blurring the roles of all players. John and I have conceived this merger to benefit our clients by bringing together the most comprehensive offering of analogue and digital services.”

Sorrell says further consolidation among the industry’s top players is inevitable following this merger which will involve over 130,000 employees and countless clients.