The tenth plague was the slaying of the first-born, and it came upon the Egyptians because of their intention to murder the men children of the Israelites at their birth, and, finally, Pharaoh and his host were drowned in the Red Sea, because the Egyptians had caused the men children of the Israelites to be exposed in the water.
Each of the plagues inflicted upon Egypt had another parallel in the cruel treatment accorded to the Israelites. The first was a punishment for the arrogant words spoken by Pharaoh, "My Nile river is mine own, and I have made it for myself."