||I think I know the wedbsite Alexander Mogilny was writing about... was it http://...XXXXXXXXXXX...
You really ought to check it out...
First he uses the calandar (so you can not really argue) to determine that
1) the expulsions from Spain and England did not occur on 9 Av
2) World War I did not start on Tbav
3) the Warsaw ghetto was not liquidated and the deportations did not begin on Tisha B'av.Neither did the Warsaw Ghetto Uprising begin on T'Bav
Regarding the mishna in taainos he says:
" M. Taanit 4:6 lists the more "traditional" events for which we mourn on 9 Av. The Gemara (bTan 29a) attempts to prove the accuracy of the Mishna's statement through available canonical material. Although there is no specific date given for narrative of the spies, the gemara uses the verses to count from the days which are given, and come up with 8 Av. Rabba citing R. Yonahan explains that the spies came back on the 8th, and the events actually happened on the 9th.
All in all a VERY good read. You should look at it.