Several websites popular with sexual predators were thwarted last month after a determined campaign by groups dedicated to eliminating the content. It was a rare victory in an unending war. In late November, the moderator of three highly trafficked websites posted a message titled R.I.P." It offered a convoluted explanation for why they were left with no choice but to close. The unnamed moderator thanked over 100,000 "brothers" who had visited and contributed to the sites before their demise, blaming an "increasingly intolerant world" that did not allow children to "fully express themselves." In fact, forums on the sites had been bastions of illegal content almost since their inception in 2012, containing child sexual abuse photos and videos, including violent and explicit imagery of infants and toddlers. In a world exploding with the imagery - 45 million photos and videos of child sexual abuse were reported last year alone - the open web is a freewheeling expanse where the underdog task of confronting the predators falls mainly to a few dozen nonprofits with small budgets. Several of those groups, including a child exploitation hotline in Canada, hunted the three sites across the internet for years but could never quite defeat them. But [a] Canadian hotline developed ... a sophisticated tool to find and report illegal imagery. The three sites were overwhelmed by the Canadian tool, which had sent more than 1 million notices of illegal content to the companies keeping them online. And last month, they were compelled to surrender.