Amazon must be spooked by the idea of writers massing against it, because over the weekend it launched its own counterrevolutionary force.

The retailer created a group called Readers United to pressure Hachette, the nation’s fourth-biggest book publisher, in its dispute with Amazon over the price of e-books. The group is a direct response to Authors United, created by the novelist Douglas Preston to persuade Amazon to stop withholding books from sale when it negotiates with publishers.

The confrontation is, some people in publishing argue, a struggle over the future of reading in our time — or at least the future of Amazon and the big New York publishers, starting with Hachette.

Authors United ran an advertisement in The New York Times on Sunday, supplying readers with the email address of Amazon’s chief executive, Jeff Bezos. Amazon’s plan for action mimicked Mr. Preston’s. In a web posting and a letter sent out to its Kindle authors, Amazon asked people to write to Hachette’s chief executive, Michael Pietsch, and provided an email address.