neologist wrote:What reference is there to verify the time between the known date of the first passover and Pharaoh's defeat in the Red Sea?
The Prophet Muhammad (Peace and blessing be upon him), when migrated to Madinah, found that the Jews of Madinah used to fast on the 10th day of Muharram (Ashoora). They said that it was the day on which the Prophet Moses (Peace be upon him) and his followers crossed the Red Sea miraculously and the pharaoh was drowned in its water.
On hearing this from the Jews, the Prophet Muhammad (Peace and blessing be upon him) said, "We are more closely related to Moses than you" and directed the Muslims to fast on the day of Ashoora.
neologist wrote:Was it a victory for Moses and the Israelites or a victory for Yahweh?
If by "Yahweh" you mean your (and my) Creator, the Creator of the Heavens and the Earth, God, Allah, then yes, it's a victory for Yahweh. It's also a victory for the believers of that time: Moses (on whom be peace) and the Israelites.
And Allah knows best.