Seventh of Adar

The Seventh of Adar, also known as Zayin Adar (ז׳ אַדָּר), is the anniversary of the birth and death of Moses in Jewish tradition. It is observed as a fast day in some Jewish communities.

Background
The Biblical sources suggesting these dates are as follows: Joshua crossed the River Jordan on the 10th of Nisan. Earlier, God had commanded Joshua to perform the crossing "in three days' time," thus this command was given on 7 Nisan. The command is specified as coming "after the death of Moses.". Moses had been mourned for 30 days after his death. Assuming that the Divine command immediately followed the end of the mourning period, Moses must have died 30 days before 7 Nisan, i.e. 7 Adar.

Practices
The Seventh of Adar is a fast day in some Jewish communities. A special tikkun is added prior to services. Jewish burial societies also often meet on the Seventh of Adar.

In Israel, the Seventh of Adar is designated as a day in remembrance of those soldiers who have fallen in war, but whose bodies have not been found or identified, in reference to the Biblical verse noting that no one knows the exact burial place of Moses "even to this day". On Mount Herzl, there is a wall with the names of 588 fallen soldiers who died in Israel with unknown grave sites.