God told Moses in the second year after leaving Egypt to count the number of men of Israel twenty years and older who could go to war. He told Moses that Aaron was to list the men. God gave Moses the name of a man from each tribe (Chiefs of Israel) to represent their tribe in the counting. The Levites were not included in this count because they were responsible for the tabernacle and its furnishings. The total number of men in Israel twenty years and older who were able to go to war was 603,550.