No Burial

In the megilla it says that the decree was להשמיד להרוג ולאבד - Lihashmid [to destroy] - refers to the mitzvos [shmad]. La-harog [killing] refers to the spirit [שפיכות דמים]. U-liabeid refers to the destruction of the physical body, and leaving it without burial [Gr"a].

The gemara in Brachos [48b] says that on the day that those slaughtered in Beitar were buried, the Rabbis decreed the bracha of Ha-tov Vi-hameitiv [the fourth bracha of bentching]. We see that despite the horrible period of destruction, there was no decree against burial. Why, in contrast, do we find that Amalek enacted a decree against burial?

When a student gets a slap in the face from the Rebbi, he hides his face in shame. When a person dies, it is a slap in the face [kviyachol] from Hashem. Since we are shamed, we hide our "face" and bury the body underground. We understand that man, in all of his glory, should ideally live forever and that death is a result of sin.  Eisav, the grandfather of Amalek said, הנה אנכי הולך למות - Behold, I am going to die. He was not embarrassed to die.

Amalek cannot stand the exalted madreiga of Klal Yisrael, that we appreciate the בושה of death. So they enacted a decree to leave the Jewish corpses without burial.....

[Rav Hutner 5738 Sefer Reshimos Lev]

Lizchus R' Shmuel Binyamin ben Tishna Rochel Leah libracha vi-hatzlacha hu vichol hanilvim alav.