The Israelites had the extraordinarily disintegrated state of the enemy to thank for the ease with which they had achieved success. The first storm subsided comparatively soon, and conquerors and conquered alike learned to accommodate themselves to the new circumstances. Then the Canaanites once more collected all their energies to strike a blow for freedom. Under the hegemony of Sisera a great league was formed, and the plain of Jezreel became the centre of the reorganised power which made itself felt by its attacks both northwards and southwards. The Israelites were strangely helpless; it was as if neither shield nor spear could be found among their 40,000 fighting men. But at last there came an impulse from above, and brought life and soul to the unorganised mass; Deborah sent out the summons to the tribes, Barak came forward as their leader against the kings of Canaan who had assembled under Sisera's command by the brook of Kishon. The cavalry of the enemy was unable to withstand the impetuous rush of the army of Jehovah, and Sisera himself perished in the flight. From that day the Canaanites, although many strong towns continued to be held by them, never again raised their heads.
After these occurrences some further changes of a fundamental character took place in the relations of the tribes. The Danites proved unable to hold against the forward pressure of the Philistines their territory on the coast to the west of Benjamin and Ephraim; they accordingly sought a new settlement, which was found in the north at the foot of Hermon. In this way all the secondary tribes westward of Jordan (Asher, Naphtali, Dan) came to have their seats beside each other in the northern division of the land. Eastward of Jordan, Reuben rapidly fell from his old prominence, sharing the fate of his next eldest brethren Simeon and Levi. When Eglon of Moab took Jericho, and laid Benjamin under tribute, it is obvious that he must previously have made himself master of Reuben's territory. This territory became thenceforward a subject of constant dispute between Moab and Israel; the efforts to recover it, however, did not proceed from Reuben himself, but from Gad, a tribe which knew how to assert itself with vigour against the enemies by which it was surrounded. But if the Hebrews lost ground in the south, they materially enlarged their borders in the north of the land eastward of Jordan. Various Manassite families, finding their holdings at home too small, crossed the Jordan and founded colonies at Bashan and northern Gilead. Although this colonisation, on account of the rivalry of the Aramaeans, who were also pressing forward in this direction, was but imperfectly successful, it nevertheless was of very great importance, inasmuch as it seemed to give new strength to the bonds that united the eastern with the western tribes. Not only was Gilead not lost; it even became a very vigorous member of the body politic. /1/
— Footnote 1. It is probable that Manasseh's migration to the territory eastward of Jordan took place from the west, and later than the time of Moses. The older portions of the Hexateuch speak not of two and a half but only of two trans-Jordanic tribes, and exclude Manasseh; according to them the kingdom of Sihon alone was subdued by Moses, not that of Og also, the latter, indeed, being a wholly legendary personage. In the song of Deborah, Machir is reckoned among the western tribes, and it was not until much later that this became the designation of the Manassites eastward of Jordan. It is also worth noticing that Jair's colonisation of northern Gilead did not take place until the time of the judges (Judges x. 3 seq.), but is related also in Num. xxxii. 39-42. — Footnote
The times of agitation and insecurity which followed upon the conquest of Palestine invited attacks by the eastern nomads, and once more the Israelite peasantry showed all its old helplessness, until at last the indignation of a Manassite of good family, Gideon or Jerubbaal, was roused by the Midianites, who had captured some of his brothers and put them to death. With his family, that of Abiezer, he gave pursuit, and, overtaking the enemy on the borders of the wilderness, inflicted on them such chastisement as put an end to these incursions. His heroism had consequences which reached far beyond the scope of his original purpose. He became the champion of the peasantry against the freebooters, of the cultivated land against the waste; social respect and predominance were his rewards. In his native town of Ophrah he kept up a great establishment, where also he built a temple with an image of Jehovah overlaid with the gold which he had taken from the Midianites. He transmitted to his sons an authority, which was not limited to Abiezer and Manasseh alone, but, however slightly and indirectly, extended over Ephraim as well.
On the foundations laid by Gideon Abimelech his son sought to establish a kingship over Israel, that is, over Ephraim and Manasseh. The predominance, however, which had been naturally accorded to his father in virtue of his personal merits, Abimelech looked upon as a thing seized by force and to be maintained with injustice; and in this way he soon destroyed those fair beginnings out of which even at that time a kingdom might have arisen within the house of Joseph. The one permanent fruit of his activity was that Shechem was destroyed as a Canaanite city and rebuilt for Israel. /1/
— Footnote 1. On the narratives contained in the Book of Judges see Bleek, Einl. ins Alte Testament (4th ed.), 88-98, and especially the sections on Barak and Sisera, Gideon, Jephthah, Samson, the Danite migration, and the Benjamites of Gibeah (93-98). — Footnote
The most important change of the period of the judges went on gradually and in silence. The old population of the country, which, according to Deuteronomy, was to have been exterminated, slowly became amalgamated with the new. In this way the Israelites received a very important accession to their numbers. In Deborah's time the fighting men of Israel numbered 40,000; the tribe of Dan when it migrated to Laish, counted 600 warriors; Gideon pursued the Midianites with 300. But in the reigns of Saul and David we find a population reckoned by millions. The rapid increase is to be accounted for by the incorporation of the Canaanites.
At the same time the Hebrews learned to participate in the culture of the Canaanites, and quietly entered into the enjoyment of the labours of their predecessors. From the pastoral they advanced to the agricultural stage; corn and wine, the olive and the fig, with them are habitually spoken of as the necessaries of life. It was not strange that this change in the manner of their everyday life should be attended with certain consequences in the sphere of religion also. It is inconceivable that the Israelites should have brought with them out of the desert the cultus they observed in the time of the kings (Exod. xxii. xxiii. xxiv.), which throughout presupposed the fields and gardens of Palestine; they borrowed it from the Canaanites. /1/
— Footnote 1. In the earliest case where the feast of the ingathering, afterwards the chief feast of the Israelites, is mentioned, it is celebrated by Canaanites of Shechem in honour of Baal (Judges ix. 27). — Footnote
This is confirmed by the fact that they took over from these the "Bamoth" or "high places" also, notwithstanding the prohibition in Deuteronomy xii.