If I may quote from the article, which is not only true, but pretty hilarious.
"It would take a hefty monograph to tally up all the prophesied and discarded Doomsdays littering the eschatology of the Watch Tower Bible and Tract Society of Pennsylvania, or Jehovah’s Witnesses.
The Society’s founder Charles Taze Russell, who had only several years of schooling but a great deal of business sense, at first affiliated himself with a group that expected the world to end in 1873. When that did not happen, the date was moved to 1874. When nothing happened in 1874, the group decided that the Second Coming had actually taken place as planned, and that Christ was here in the world, only he was invisible. It was then decided that the actual visible and palpable end of the world would come in 1914. This gave Russell and his colleagues a full forty years to proceed with their mission of saving lost souls without being undermined by their own predictions.
The year 1914 saw the Great War break out in Europe, but the world still refused to end. This was highly inconvenient, because Russell had promised eternal life to “millions” who witnessed the events of 1914. And so after his death in 1916, Watch Tower publications continued to push back the fateful day as became necessary. First it was moved to October 1, 1917. Then to 1925. From the mid-1930s to early 1940s, pamphlets said it was “months away.” Later another delay was effected until September 5, 1975. All the while, the generation of 1914 continued to die off at normal pace, which was making some people antsy. By 1995, Russell’s teaching about its elect immortal millions had to be discarded. These days, a Watchtower tract is likely to talk about Armageddon being seen by the “anointed” whose lives overlap with the lives of those who saw 1914, effectively pushing the end of things many vague decades into the future."