Six hundred is a great number of chariots, and that is the number of only his best ones. He also took along all the other chariots of Egypt and his army. He may have wanted to give a great show of strength, but this also seems to me to be an indication that there must have been a significant number of Israelites for Pharaoh to have bothered bringing all his troops.
Pharaoh is still fighting against God. Even the death of his own firstborn son (as well as the deaths of the firstborn sons of all of the households of Egypt) has not convinced him of God's power and control over his life. Apart from being determined to get the Israelites to return to Egypt, Pharaoh seems to be bent on one last mighty effort to prove that he is in control. In effect, Pharaoh is still raging against God.
Pharaoh's chariots and army have no problem catching up with the escaping Israelites, who for their part had marched out boldly. Pharaoh and his army overtake the Israelites as they camped by the sea, near Pi Hahiroth, which is opposite Baal Zephon.
So, when Pharaoh caught up to them, the Israelites were camped somewhere which has to satisfy all of the scriptural criteria:
- They are near Pi Hahiroth.
- Pi Hahiroth is 'opposite' Baal Zephon. I suppose that could mean either 'directly across from' or 'parallel to' Baal Zephon.
- They are camped by the sea. Perhaps this small detail will help eliminate other proposed sites.
- Pi Hahiroth is to the east of Baal Zephon.*
- Pi Hahiroth is also near Migdol.*
- "The Israelites set out from Rameses on the fifteenth day of the first month, the day after the Passover."(Numbers 33:3 NIV)
- Rather than just going straight up north toward Canaan, "...God led the people around by the desert road toward the Red Sea." (Exodus 13:18 NIV)
- "The Israelites left Rameses and camped at Succoth." (Numbers 33:5 NIV)
- "They left Succoth and camped at Etham, on the edge of the desert." (Numbers 33:6 NIV)
- "They left Etham, turned back to Pi Hahiroth, to the east of Baal Zephon, and camped near Migdol." (Numbers 33:7 NIV)
*Numbers 33:7 is where we get facts four and five in the numbered list of scriptural criteria for the location of Pi Hahiroth, that 4) Pi Hahiroth is to the east of Baal Zephon and 5) Pi Hahiroth is also near Migdol.