Pharaoh became very angry, and instead of letting the Jews go, he made them work even harder.
The Eternal then sent plagues on the Egyptians.
After each plague, Pharaoh almost relented, but in the end, he always hardened his heart and would not let the Jews go.
God first turned all the rivers and all the waters that were in Egypt into blood.
Second, frogs came to the land.
Then came the lice, the flies, then livestock pestilence, boils, the hail, the locusts, the darkness, but still, Pharaoh was stubborn.
The last plague was the cruellest. The Eternal killed all the firstborn of Egypt, only sparing the house of the Jews, for he had told them beforehand to mark their doorposts with blood, and the angel of death would thus avoid them.
After the tenth plague, Pharaoh was utterly broken, for he had lost his firstborn son. He finally let the Jews go, and after many years of slavery, they were set free.