What does 1 Samuel 4:9 mean?

From a human perspective, it would seem the army of the Philistines had the clear advantage over Israel. In their initial face-off, the Philistines had killed numerous Israelite soldiers (1 Samuel 4:2) and attained decisive victory.

However, neither the Philistines nor the Israelites were weighing their expectations for the next battle against human concerns. The common thinking of the day was that gods won or lost wars to each other. When one nation defeated another, most people believed that the god of that nation had been proven stronger on the field of battle. With the ark of the Lord now nearby, the Israelites were confident He would win the victory for them. The Philistines were overwhelmed with fear that the God who defeated the mighty Egyptians would destroy them, as well (1 Samuel 4:4–8).

Still, the Philistines were warriors. They understood that whatever the gods might do, they had to step up and fight like men. They rouse each other to take courage and fight for all they're worth. After all, they do not want to become slaves to the "Hebrews." In this context, "Hebrews" appears to be the Philistines' way of indicating that this people group had come from beyond the Euphrates or beyond the Jordan. It seems the term "Hebrews" is used to distinguish between Israelites and other groups whereas the Israelites were identified, among themselves, by their patriarch's name.

This verse reveals that the Philistines had already taken some of Israel's land and people. Some Israelites already lived as slaves to the Philistines, which is why Israel had come to take their stand in this place (Judges 13:1). The stakes were not only for land but also for forced servitude.