Then the Lord said to Moses, “Pharaoh’s heart is unyielding; he refuses to let the people go. Go to Pharaoh in the morning as he goes out to the river. Confront him on the bank of the Nile, and take in your hand the staff that was changed into a snake. Then say to him, ‘The Lord, the God of the Hebrews, has sent me to say to you: Let my people go, so that they may worship me in the wilderness. But until now you have not listened. Exodus 7:14-17
Then the Lord said to Moses, “Stretch out your hand toward the sky so that hail will fall all over Egypt—on people and animals and on everything growing in the fields of Egypt.” When Moses stretched out his staff toward the sky, the Lord sent thunder and hail, and lightning flashed down to the ground. Exodus 9:22-24
Then the Lord said to Moses, “Go to Pharaoh, for I have hardened his heart and the hearts of his officials so that I may perform these signs of mine among them that you may tell your children and grandchildren how I dealt harshly with the Egyptians and how I performed my signs among them, and that you may know that I am the Lord.” Exodus 10:1-3
There were ten plagues. God gave Moses the power of leader and allowed him to set his people free. God sent the plagues all through Egypt so the Pharaoh would let the Hewbrews go to freedom with Moses. The plagues scared the Pharaoh which after the tenth, and worst one, he allowed them to go to freedom.