‘ And Manasseh, did not drive out the inhabitants of Bethshean and her towns, nor Taanach and her towns, nor the inhabitants of Dor and her towns, nor the inhabitants of Ibleam and her towns, nor the inhabitants of Megiddo and her towns. But the Canaanites would dwell in the land.'
The tribe of Manasseh was divided in two, one section being Beyond Jordan, and the other in the section of Canaan north of Ephraim and south of Zebulun and Issachar. Their territory included the powerful Canaanite fortresses mentioned and much lowland territory. This territory had a strong Canaanite presence, unlike the hill country.
But there were large forests which would make infiltration possible until Manasseh was strong enough to take over the territory, apart from the large cities, and then finally to take over the large cities themselves. These were too powerful to be overcome immediately, but there would come a time when it was possible, and yet when that time came Manasseh compromised with the Canaanites. That is the main point here, that they allowed the Canaanites to remain even when they could have done something about it, and that meant fraternising with them and assimilating their ways and their debased religion.
Megiddo. In terms of the times Megiddo was a huge city. Situated at one side of the Valley of Jezreel it guarded the main trading route between Mesopotamia and Egypt. It had previously been under Egyptian control, but at this time Egypt was too concerned with its own internal affairs to be bothered about Megiddo. It must have seemed invincible, but it was totally destroyed c.1150 BC and replaced temporarily by a small village. We can note how it is not mentioned in the song of Deborah, which rather mentions another powerful city, ‘Taanach by the waters of Meggido' (Judges 5:19), demonstrating the accuracy of the song. Its king was earlier slain by Joshua (Joshua 12:21) but the city itself resisted invasion (Joshua 17:11-12) and survived until Israel became too strong for it to do so any longer. Its final destruction was probably by Israel who then occupied the mound. It was later rebuilt and became a powerful Israelite city.
The same applied to Taanach. Taanach was on the other side of the Valley of Jezreel. It is mentioned in both Egyptian and Assyrian records. It too held out for many years but it too was finally destroyed by the Israelites. Ibleam, which was south of Megiddo and Taanach, was also a powerful fortress city. Dor was on the coast, and on the arrival of the Philistines, ‘the Sea People', was, along with Bethshean (1 Samuel 31:10), which also protected the Valley of Jezreel, occupied by them. Both continually resisted Israelite attack and once occupied by the Philistines and their allies were invulnerable to it, but were eventually defeated, although possibly not until the time of David.