Aish.com has an article by Rabbi Pinchas Stopler on the mystery of Lag Ba'Omer.
As Rabbi Stopler notes, Lag Ba'Omer is really Yom Yerushalyim, the anniversary of the day Bar Kokhba's army captured Jerusalem. I have also heard – but cannot source – that Lag BaOmer is the day the revolt began. Rabbi Stopler is careful to label Bar Kokhba a "failed messiah" rather than a false one.
But Rabbi Stopler raises a question that he leaves unsatisfactorily answered: Why do we mourn 49 days for the deaths of Rabbi Akiva's disciples (remember, Lag Ba'Omer is the day that the mysterious "plague" that killed 24,000 of Rabbi Akiva's followers stopped), but only one day for the destruction of the Temple and the end of the Second Commonwealth?
Rabbi Akiva was Bar Kokhba's chief backer. He sold Bar Kokhba's mission to the rabbis and to the masses. He did so by declaring Bar Kokhba the long-awaited messiah.
At first the revolt succeeded. Bar Kokhba's forces decimated the Romans and took Jerusalem. He began to build (and some say, completed building) the Third Temple. But years into the revolt the Romans began to regain the upper hand. It would appear that it is at this crucial point that Rabbi Akiva's disciples erred. But what was that error?
Rabbi Elazar, accused of betraying Betar to the Romans, was executed by Bar Kokhba against the will of Rabbi Akiva. As Rabbi Stopler notes, the common explanation among today's Orthodox scholars is that it was the Jewish-Christians, not Rabbi Elazar, who betrayed Betar and caused the death of more than 500,000 Jews.
But is that really so? While rabbinic elites of the time certainly persecuted the early Christians, there is no evidence that Bar Kochba or the Jewish masses did so, even during the years Bar Kochba reigned. There also are no known contemporaneous sources that implicate the Christians, and Judaism has no historical memory of a Christian betrayal of Betar. It would also appear that Christians served in Bar Kochba's army, and that their community had much to lose from a Roman victory.
So who really betrayed Betar?
While we cannot answer that question with absolute certainty, it would seem that Rabbi Elazar – or another of Rabbi Akiva's student-colleagues – actually did.
When Rabbi Elazar was executed by Bar Kochba – who was, after all both king and the declared redeemer, and was well within his rights to execute anyone – Rabbi Akiva withdrew support for the revolt.
Rabbi Akiva seems to have envisioned a theocracy where the king would be a military leader and figurehead subservient to the rabbis. If so, Rabbi Akiva either had a radically different understanding of the messiah than our extant Jewish tradition or his messianic crowning of Bar Kochba was a ploy to rally the masses behind the revolt.
As Rabbi Stopler points out, we must understand that the Talmud presents the story of Rabbi Akiva's students in veiled language, in part due to the political climate of that day. Open endorsement of the revolt was too dangerous, even more than 100 years later.
So, what really happened? Perhaps this:
After its initial successes, Bar Kokhba's revolt began to fail. As it did, dissent became rife in the rabbinic elite. As dissent widened, Rabbi Akiva's position as the power behind Bar Kokhba's throne diminished. Further, Bar Kokhba ruled as a king – not as Rabbi Akiva's puppet. In imitation of the deal Rabbi Yochanan Ben Zakai struck with the Romans almost 70 years earlier, some of the rabbis sought to save themselves from the impending destruction and deal with the "Bar Kokhba problem" at the same time. They attempted to strike a deal with the Romans – allow us to escape to freedom and Bar Kokhba is yours.
But Bar Kokhba uncovered the plot – not in time to save Betar but in time to punish at least one of the plot's ringleaders.
Lag Ba'Omer is therefore a celebration of military victory, the holiday Jews refused to forget even after the revolt failed.
The mourning practices of Sefirat HaOmer that surround Lag Ba'Omer commemorate the deaths of hundreds of thousands of Jews who died fighting under the banner of a false messianic idea propagated by Rabbi Akiva and his colleagues for political purposes. The mourning period is suspended only for Lag BaOmer – which is both the anniversary of day the revolt began and the anniversary of the day Jerusalem was liberated by Bar Kokhba – the day those Jews fought so hard to achieve, and continues until it is lifted by the Biblical holiday of Shavuot.
Shiva, the period of mourning observed on the death (God forbid) of a near relative is 7 days long. It may then follow that the mourning period for an entire nation is 49 days long, based on the Sabbatical cycle which is 7 years long and exists for seven cycles (49 years) with the 50th year being the Jubilee, a national holiday year.
(This may also be the meaning of the Talmudic story regarding Rabbi Shimon Bar Yochai, who tells his student in a dream not to fast or mourn on the anniversary of Rabbi Shimon Bar Yochai's death even though the custom was to fast and mourn on a yartzeit. Rabbi Shimon Bar Yochai died on Lag Ba'Omer - Yom Yerushalyim.)
Why did the 'plague' that killed 24,000 of Rabbi Akiva's students 'stop' on Lag BaOmer? To show that support for the revolt was not the cause of their deaths: Askara – the plague – was.
Askara, croup in English, is a viral, primarily early childhood disease and is rarely fatal. Could those 24,000 disciples have died from croup? And, if so, why did no others die with them?
I propose that askara (spelled with a samekh) should be read as "azkara" spelled with a zayin. (The samekh and zayin are interchangable letters).
If this is done the plague becomes clear. Azkara means a formal, ritualized act of remembering an event. It is most often used to denote memorial ceremonies held in rememberence of tragedies.
Rabbi Akiva's disciples perished because they did not remember (azkara) the lessons of the destruction of the Second Temple and in order that their deaths serve as an azkara for all time.
Those rabbinic leaders fostered division between themselves and between themselves and the common Jews.
When Bar Kokhba's early victories reversed and the revolt began to falter, Rabbi Akiva and his followers gave up on the revolt they had so stongly promoted and tried to save their own skins at the expense of the common Jews and Bar Kokhba's army. They followed the example of Yokhanan Ben Zakai, who asked the Romans to save Yavne and its sages, but did not ask the Romans to spare the common Jews, tens of thousands of whom were consequently slaughtered by the Romans.
The disciples tried to strike a similar deal with the Romans – allow us to escape to freedom and Bar Kokhba and the common Jews are yours.
Bar Kokhba's discovery of the plot was too late to save Betar or the more than 500,000 Jews who perished there.
Without interference, Bar Kokhba may have survived to fight another day. He was not a false messiah, nor was he a failed one.
Bar Kokhba was a betrayed messiah. That is the true lesson of Lag Ba'omer.