Sforno on Exodus 13:18/ספורנו על שמות י״ג:י״ח

1דרך המדבר ים סוף, that they should march to the Sea of Reeds via the desert. On that route they would neither encounter travelers headed in the direction of Egypt, nor would they encounter travelers who had come from Egypt who could report that Pharaoh was going to chase them, until Pharaoh would actually catch up with them by which time a “voluntary” return to Egypt and slavery would not be of any advantage to them anymore, as their surrender would not then be acceptable to Pharaoh.

2וחמושים עלו, although they had left Egypt fully armed. They did not have the courage to face the Egyptians in combat in spite of their being armed. They felt too inexperienced to face trained warriors.