Seth had 72 conspirators to kill Osiris. They built a nicely decorated box that fitted his measurements. They threw a feast for Osiris and one after the other stepped into the box, but none would fit. When Osiris stepped in, the slammed the lid and threw the coffin into the Nile.
Isis, with the help of others located the body. But when Seth learned about it, he tore the body apart and scattered it throughout Egypt. Isis then was able to reassemble 13 parts of Osiris' body, the only part that was missing was his phallus, which she replaced by a golden one, and resurrected him long enough to become impregnated with Horus.
Isis & Horus
The date of Osiris' death was the 17th of the month of Athyr. Of course, it was not the end of that battle. Later on Seth poked out one eye of Horus. Flashing the one eye tells you: We have the eye of Horus.
It is the old story of who is going to rule. One is the ruler, the other wants to be the ruler.
Stories like this get recycled again and again and..... Nothing new under the sun. Some might trick you into thinking that this about humanity's liberation, but in the end it is the exact opposite. Rulership over humanity is desired.