BCHF
- Julian's attempt to rebuild the Temple
https://earlywritings.com/forum/viewtopic.php?p=206708#p206708
Yonathan Adler on Facebook:
On this day, 18 Iyar 363 CE, a great earthquake rocked the Levant.
Countless people were killed, and buildings collapsed.
Among the structures destroyed—so it seems—was the Third Jewish Temple, then under construction in Jerusalem at the order of the Roman emperor Julian (“the Apostate”).
The anniversary of the tragedy—so it seems—was marked by Jews through an annual fast day.
Wishing a meaningful day to all those who commemorate it.
Tonight marks the 18th of Iyar according to the Jewish calendar, a date that is widely celebrated as a minor holiday called “Lag Ba‘Omer”. It seems, however, that the date was originally commemorated as a fast day and a time of mourning.
An inscription found on plaster fragments from an internal wall in the Rehov synagogue (dated 5th to 7th century CE) provides a list of fast days. The 18th of Iyar is one such fast day, although no explanation is given for why it should be so.
Several pieces of evidence, however, point to the earthquake which did tremendous damage throughout Palestine in 363 CE as having taken place on the 18th of Iyar.
At the time, the emperor Julian (“the Apostate”) had allowed the Jews to rebuild their temple in Jerusalem, and work on the foundation had already begun. The earthquake appears to have been one of the impediments to the project which eventually was abandoned completely with the death of Julian a few weeks later. It seems likely that the 18th of Iyar was proclaimed a fast day in commemoration of these calamitous events.
How the day of mourning turned into a day of celebration is a story unto itself, but it would take many centuries for this to develop.
For an accessible publication on the list of fast days from the Rehov synagogue wall plaster fragments (an inscription distinct from the mosaic inscription on its floor), see Haggai Misgav's article linked in the first comment (the drawing below comes from there).