1)
Why must Hashem return them to their land?
1.
'Rashi': When the enemy defeats them, they take whatever captives they can and bring them to another land.
2.
Malbim (Melachim I, 8:34): Verse 36 below discusses when Yisrael left the land. Here, Yisraelim left their cities to fight the enemy within Eretz Yisrael; Hashem will return them to their cities.
