Final answer:
Moses recounts the census of the Israelites in Numbers 1 to determine the number of men available for military service and to organize the tribes and divisions.
Step-by-step explanation:
The event that Moses recounts in Numbers 1 regarding the leadership of Israel is the census of the Israelites. In Numbers 1, Moses is instructed by God to take a census of all the men who are twenty years old or older and able to serve in the army. This census was conducted to determine the number of men available for military service and to organize the Israelites into their respective tribes and divisions.