God in His love for Israel had frequent censuses taken of them, so that He might accurately estimate His possession. In scarcely half a year they were twice counted, once shortly before the erection of the Tabernacle, and the second time a month after its dedication. On the first day of the month of Iyyar, Moses received instructions to take a census of all men over twenty who were physically fit to go to war.
He was ordered to take Aaron as his assistant, so that in case he should overlook some of the men Aaron might remind him of them, for "two are better than one." They were also to take as their subordinate assistants Eleazar and Ithamar, Aaron's sons, and a man each from the several tribes. These twelve men were appointed not only to conduct the census, but also to look after the spiritual welfare of their respective tribes, the sins of which would be upon their heads unless, with all their powers, they strove to prevent them.
Moses and Aaron nevertheless adjured the princes of the tribes, in spite of their high rank, not to tyrannize over the people, whereas, on the other hand, they admonished the people to pay all due respect to their superiors.