Continuing his approach of breaking promises, Pharaoh pursued the Israelites after releasing them from Egypt.
The Egyptians had already seen the ten plagues and recognised God’s power behind them. Now, in pursuit of the escapees, Pharaoh and his army saw a pillar of smoke (in daylight) and fire (at night) keeping the Israelites safe.
The Israelites, who had also seen the same miracles, were terrified when the saw the Egyptian army closing in. God needed to reassure them:
14:13-14 But Moses told the people, “Don’t be afraid. Just stand still and watch the Lord rescue you today. The Egyptians you see today will never be seen again. The Lord himself will fight for you. Just stay calm.”
The Egyptians would not have heard that. Being just as human as the Israelites, the Egyptians reasonably had no more reason to believe that a God they did not know could (or would) protect a large group of frightened, escaped slaves with only a small proportion of fighting-age men with little or no training in warfare.
Even without hearing God’s voice, the Egyptians would have seen God’s power: the Israelites walking through a sea, between two walls of water. Perhaps Pharaoh couldn’t face the humiliation of giving up. He gave the order for his army to follow the Israelites through the sea (the Bible records the army’s reluctance). The results were disastrous for the Egyptians:
14:28 Then the waters returned and covered all the chariots and charioteers—the entire army of Pharaoh. Of all the Egyptians who had chased the Israelites into the sea, not a single one survived.
Pharaoh could more easily (and safely) have kept his promise to let the Israelities go, and his army would have survived intact. Forty years later, the Egyptian army had still not recovered (Deuteronomy 11:4)
Just imagine the massacre if God had let the Egyptians through the Red Sea.