A 49 Hour Fast
Can you imagine what it must be like for Yom Kippur, the Day of Atonement, to last two days? For most of us 25 hours of fasting is quite enough. But during the Second World War, there were people who fasted for 49 hours - two days of Yom Kippur!
When the Germans invaded Eastern Europe during the Second World War, the Mir Yeshiva made a miraculous escape across Europe and Asia to Kobe in Japan. However, when the Yamim Noraim (Days of Awe) approached, they were faced with a dilemma...
Up till the time of Hillel II, the date of the festivals, Pesach, Shavuot, Succot and Rosh Hashana were established via testimony based on the sighting of the new moon. The new month was declared in Jerusalem, and it would take many days for the news to reach the furthest outposts of Jewish settlement. Those outlying communities would observe two days of Pesach and Succot etc., and thus they would be sure of observing the festival on the correct day, no matter which day had been sanctified in Jerusalem as the new moon.
Until the era of the two great Talmudic sages Abaye and Rava, the months were still established by sighting. However, from their time onward, the date of the New Moon was established by calculations alone. These computations were given to Moses at Sinai, and provided for the fixing of the beginning of each month throughout the possible span of world history. Thus all the lengths of all future months in exile were now fixed.
So why is then that if you're in New York or London or Paris, you're still keeping two days of Yom Tov? If the calendar is fixed and we know exactly which day is Yom Tov and which isn't, why can't we all keep just one day?
The answer is that our Sages made a law that we should continue to observe the two days of Yom Tov as was the custom of our forefathers.
However, when our Sages mandated the continued observance of the two-day Yom Tov in the Diaspora as a continuation of the traditions of our forebears, they deliberately omitted a two-day Yom Kippur because it would be dangerous for some people to fast for such a long period.
However, the Mir Yeshiva in Kobe was faced with a different situation:
The omission of the Sages' decree to fast two days of Yom Kippur
was because we are certain on which day Yom Kippur occurs. However,
Japan is close to the International Date Line, (a longitudinal
line which lies 180° from Greenwich) and thus there was a
real doubt as to which day it was. For this reason, there were
those of the Mir Yeshiva who felt compelled to fast for two days.
And even others who were less strong, while they could not observe
the fast itself, commemorated all the other aspects of this holiest
day(s) of the year.
- Rambam, Hilchot Yom Tov, ch. 1; Hilchot Kiddush Hachodesh, ch. 5
- "Escape to Shanghai"; Rabbi Mordechai Becher