‘ And the house of Joseph, they also went up against Bethel, and Yahweh was with them.'
It appears that Bethel, having possibly (but not necessarily) been taken along with Ai in the days of Joshua 8, had again been occupied by Canaanites after the Israelites moved on. It lay on the borders of the sons of Joseph, Ephraim and Manasseh. Therefore they combined together to take it.
“And Yahweh was with them.” Thus they would be victorious.