The book of Numbers begins, the way the book of Leviticus begins, with the Lord speaking from the Tabernacle to Moses. A year after the law was given to Israel on Mount Sinai, Israel is still camped at the base of the mountain.
God tells Moses to take a census of Israel. A previous census was taken in Exodus 30:12-16 and 38:25-28. This time the census was for determining the number of fighting men. The men 20 years old or older were to be counted and listed with the name of their clan and their family. The minimum military age in Sparta was also twenty years old, while Athenian’s military service began at eighteen. The clan would have been a sub-group of one of the twelve tribes and the family would have been a smaller sub-group within the clan. Israel: Nation-->Tribe-->Clan-->Family-->Individual.
The purpose of this census was clearly stated: To determine the number of men “who are able to serve in the army.” This may seem like meticulous details and pointless information, but it was actually the first stages of invading the Promised Land, the land promised to Abraham, Isaac and Jacob. In fact, this could have started a great stir among the people who had been camped at Mount Sinai for a year. The Lord was making war preparations!