In the 1970s, Harlequin reached its peak in dominating English-language mass market romance. At the end of the decade, it broke ties with its US distributor, Simon & Schuster's Pocket Books, planning to take on distribution in the itself. The US publisher immediately poured money into a new romance imprint that would fill the exact spots on the rack once reserved for Harlequin: the two companies' contract expired at the end of 1979, and Simon & Schuster launched Silhouette Romance in 1980. Thus began a publishing war that would bleed over a hundred million dollar and release mass market romance from the homogenized grip of the precisely branded Harlequin, leading to an explosion of experimentation and variation in the early 1980s.
Silhouette was able to do what Harlequin considered unthinkable — challenge it — because of three main factors. First, Harlequin had underestimated both their distribution power and their willingness to throw millions of dollars into building a juggernaut from the ground up, including an initial $4 million ad campaign that would soon balloon into the tens of millions. (Grescoe notes that later ads crowed, "Sorry Harlequin, millions of American women are being unfaithful to you".) Second, Simon & Schuster took advantage of Mills & Boon's lack of interest in American authors. As indicated by Mills & Boon's now legendary rejection of Nora Roberts ("they already had their American author"), many excellent manuscripts by American authors were available for Silhouette's editors to scoop up. Third, Simon & Schuster wasn't afraid of playing dirty. They lured away not only a Harlequin executive (P.J. Fennell), but also major Harlequin writers to write for their imprint. Silhouette Romance #1 was written by Anne Hampson, whose work had also launched Harlequin Presents: it does not seem a coincidence that Silhouette chose this author with a book entitled Payment in Full — evoking a revenge plot — for their #1. Further, they mimicked the cover design of Harlequin Presents so closely that Harlequin sued them over it, claiming that buyers would buy Silhouettes thinking they were Harlequins. This copy of Silhouette Romance #1 shows how closely Simon & Schuster recreated the look of Harlequin Presents. Dick Snyder, president of Simon & Schuster, denied any intentional imitation of the Harlequin design, dismissing the suit as Harlequin "trying to copyright the color white" (quoted in Markert). But the New York judge issued an injunction against Silhouette, after which new titles were issued with the now iconic purple-border design.

Read more: Romney, The Romance Novel in English: A Survey in Rare Books, 1769-1999 (item 50); Grescoe, The Merchants of Venus: Inside Harlequin and the Empire of Romance (especially "War of Love: Silhouette Verses Harlequin"); Jensen, Love's Sweet Return: The Harlequin Story; Markert, Publishing Romance: The History of an Industry, 1940s to the Present.