1 Then Moses and the Israelites sang this song to the LORD :
"I will sing to the LORD,
for he is highly exalted.
The horse and its rider
he has hurled into the sea.
The Children of Israel have just left Egypt after 430 years in captivity. Moses has already gone to Pharaoh and said "Let my people go!" God led the Children of Israel to the Red Sea with a pillar of cloud by day and a pillar of fire by night. They camped by the Red Sea near Pi Hahiroth, between Midgol and the sea, directly opposite Baal Zephon. (Ex. 14:2) as Pharaoh's armies approached in chariots from Egypt.
All the Children of Israel could think was that they were going to die in the desert at the hands of Pharaoh's armies and that they were never going to reach the Promised Land. But Moses assured them that the LORD would fight for them--they only needed to be still (sounds like Ps. 46:10, doesn't it?). We all know the rest of the story: Moses stretched out his hand over the Red Sea and "all that night the LORD drove the sea back with a strong east wind and turned it into dry land." (Ex. 14:21) The Israelites marched through on dry ground with a wall of water on their right and left.
Pharaoh's armies pursued them, and all the horses and chariots and horsemen followed them into the sea. Then God fought for the Israelites. He made the wheels of the chariots come off. He threw the Egyptians into so much confusion that even they knew that God was fighting for the Israelites. At daybreak, after the Children of Israel were safely on the other side, having been protected all night long by the angel of God, Moses stretched out his hands and the water of the Red Sea came crashing down on the Egyptian army, drowning them all.
What follows in Exodus 15 is known as the Song of Moses and Miriam (his sister). It is the joyful response of an entire nation of people who witnessed their salvation and the wonders of God. It is a good example of the "new song" that we are encouraged to sing to the LORD. When God surprises us with His grace, mercy, blessings, and deliverance, our natural reaction should be to sing to Him and praise His name for all his wonderful acts. We certainly don't deserve any of them.