‘ And they went out, they and all their hosts with them, many people, even as the sand which is on the seashore for multitude, with very many horses and chariots. And all these kings met together, and they came and pitched together at the waters of Merom, to fight with Israel.'
This was something which Joshua had not faced before and for which YHWH had been preparing him. This was a major army and was equipped with many horses and chariots. Israel probably had no horses, and certainly no chariots. Thus they would have to face this great army on foot.
So the sections of this great army went out from their differing headquarters and met together under their kings at some rendezvous from where they proceeded to the waters of Merom. Merom is mentioned in the lists of Tuthmosis III. One possible site is the village of Meiron near Safed, which is near springs that feed the Wadi Leimun (or Wadi Meiron). Another is Maroun er-Ras which is above a valley leading to the Huleh basin north of Hazor. There they prepared ‘to fight against Israel'.