John Calvin Commentary Joshua 4:12

"And the children of Reuben, and the children of Gad, and the half-tribe of Manasseh, passed over armed before the children of Israel, as Moses spake unto them:" — Joshua 4:12 (ASV)

And the children of Reuben, etc. He mentions the expedition of the two and a half tribes, since they did not set out to engage in warfare on their own account, but to assist their brothers, by whose valor their own possession had been obtained in seizing the land of Canaan. Moses had placed this obligation on them, and they had bound themselves by oath to accompany the rest of the people until all had obtained a quiet settlement.

They again made the same promise when the camp was about to be moved, as we saw in Joshua 1. But from the narrative here, we gather that only a part was selected, for the number amounts to only forty thousand—that is, a third, or about a third, of the number ascertained by the census taken shortly before.

Now, since they are everywhere said to have performed their promise, it may probably be conjectured that it was not Moses' intention strictly to insist that all who had assented should leave their wives and children and do military service in the land of Canaan until it was wholly subdued.

And certainly, it would have been harsh and cruel to leave an unwarlike multitude unprotected in the midst of many hostile nations. Nor would the remains of the enemy, assisted by neighboring nations, have long delayed in taking advantage of such an opportunity to avenge themselves by massacring the women and children.

It was necessary, therefore, in a country not yet sufficiently pacified, to permanently retain a force sufficient to prevent incursions. Moses was not of such a stern nature as not to provide for the helpless. Indeed, his prudence and equity would never have allowed him to leave a territory recently seized by arms unoccupied by a body of troops.

We may add that such an immense crowd would have impeded rather than assisted the acquisition of the land of Canaan. All that Moses required, therefore, was simply that the Reubenites and Gadites should not, while their brothers were engaged in carrying on the war, remain indolently at home and eat their food at ease without giving any assistance to those to whom they were indebted for having obtained the inheritance.

And the good faith of the forty thousand was proven by their not declining the burdens, toils, and perils of warfare, while the remainder of their own tribes were enjoying quiet. They might readily have alleged that they were as entitled as the others to exemption; but by proceeding with alacrity, after the levy was made, to obey the orders given them, without envying the immunity given to their brothers, they showed that they were voluntarily and heartily disposed to do their duty.

At the same time, it is not doubtful that by accepting the flower of their tribes, the basis for complaint and quarrel was removed. For it could not have been justly maintained that even the aged and worn out, or the young and feeble, were not to be spared. Some, perhaps, may be inclined to conjecture that the army was raised not by choice but by lot, though it seems more likely to me that all who were most robust and best able to bear fatigue were enrolled.