I once saw a documentary where one of their leaders claimed that they had never tried to predict the end of the world.
My memory is a little rusty. How many times did they actually predict the end?
The former member of Jehovah's Witness Governing Body Raymond Franz gave a great account of this in his book Crisis of Conscience
not long before his death. You can read the chapter about the 1914 generation here: http://www.scribd.com/doc/84300150/10/AND-%E2%80%9CTHIS-GENERATION%E2%80%9D
Also extremely informative regarding your specific question is W. Bednarski, Armageddon in 1975: Probability or Possibility?
Armageddon was originally, according to Charles Taze Russell, to occur in 1914. When this did not happen, 1914 shifted to the date of the supposed invisible return with Armageddon to take place within the lifetime of the generation of the "faithful eyes" (the Watchtower interpretation of "every eye will see him" (Rev 1:17) is "every faithful eye") which supposedly witnessed it. The Watchtower use to emphasize that those who witnessed the return had to be old enough to rationally comprehend it and that they were at least in their teens in 1914. 1914 is now almost a hundred years ago (teens in 1914 would already be long since dead), and is continuing to -s-t-r-e-t-c-h- the Watchtower's hermeneutical creativity to fascinating limits. As the clock continued ticking numerous clever reinterpretations of the timespan of the "generation" which could not pass away before Armageddon took place, the most recent being a new "two overlapping generations" view, which arrives just in time, so it seems to many faithful Jehovah's Witnesses, to save their paradigmatic day with New Light.
Here is a short outline of some key persons, prophecies, and events, but do read the chapter Raymond Franz, it is much more informative and lively, and do at least skim W. Bednarski.
1896 The Watchtower Bible and Tract Society, Inc. is incorporated by Charles Taze Russell
(1852– Oct 31, 1916). Russell published Studies in the Scripture (some published posthumously).http://www.jwfacts.com/watchtower/1800s.php
1913: Mrs. Russell brought suit for divorce from her husband on the grounds of "his conceit, egotism, domination, and improper conduct in relation to other women." A large number left the movement as a result of evidence presented during court proceedings.
1914 Russell's predicted date for the battle of Armageddon.Before 1914 the Watchtower Society taught 1914 would be the "end" of the system of things, the conclusion of Armageddon and the start of the earthly paradise. In 1915 the Watchtower adopted it's current claim to have accurately predicted 1914 to be the "start" of the conclusion of this system of things marked by an "Invisible Return" of Jesus Christ.
1916 J.F. “Judge” Rutherford leads the Watchtower Society after Russell’s death. Russell’s doctrines had been largely limited to speculations about the end of time and man’s nature.
1918 Rutherford proclaims the resurrection will take place in 1925 and that "millions now living will never die."
1920 "Millions Now Living Will Never Die," a 128-page booklet is published, proclaiming "we may expect 1925 to witness the return of these faithful men of Israel [Abraham, Isaac, and Jacob] from the condition of death, being resurrected and fully restored to perfect humanity and made the visible, legal representatives of the new order of things on earth." Millions Now Living Will Never Die
p. 88. At this time the general resurrection, Rutherford said, would also take place. People alive at that time could expect to never die. http://www.jwfacts.com/watchtower/1800s.php
1924 "The Way to Paradise" is published, emphasizing the pivotal events of 1925.
"The Bible and "The Bible in Stone" [the pyramid of Giza] give the date 1914: for the beginning of the great change. History proves that the ouster proceedings began promptly on time. Prophecy indicates that 1925-1926 will see the greater part of the ousting completed. All the world's statesmen are dreading the next few years... We should, therefore, expect shortly after 1925 to see the awakening of Abel, Enoch, Noah, Abraham, Isaac, Jacob, Melchisedec, Job, Moses, Samuel, David, Isaiah, Jeremiah, Ezekiel, Daniel, John the Baptist, and others mentioned in the eleventh chapter of Hebrews... No doubt many boys and girls who read this book will live to see Abraham, Isaac, Jacob, Joseph, Daniel, and those other men of old come forth in the glory of their better resurrection, of perfect in mind and body. It will not take long for Christ to appoint them to their post of honor and authority as his earthly representatives. The world and all the present conveniences will seen strange to them at first, but they will soon become accustomed to the new methods. They may have some amusing experiences at first; for they never saw telephones, radios, automobiles, electric lights, aeroplanes, steam engines, and many other things so familiar to us" (The Way to Paradise
(1924) pp.p.171, 224, 226).
"Seventy times 50 [Jubilee years] are 3,500. The whole period would therefore have been 3,500 years from the time the Jews entered Canaan until all the types would have been fulfilled. As they entered Canaan 1,575 years before Christ there would be 1,925 years of types after Christ, or 1925 A. D"( ibid, p.223).
Undertakers would be out of jobs "Some of them used to be undertakers; but since there are no more people dying, they have had to seek some new occupation. Their experience as undertakers prepared them to become decorators with very little difficulty" (ibid, p.228).
1926: Beth Sarin is constructed.
1931 Name “Jehovah’s Witnesses” is adopted.
1942 a drastic turn.