How did helots allow spartan society to focus on war?

 They were engaged in farming while the Spartans could engage in military training for the needs of the war

Explanation:  Helots were a class of people in ancient Greece, in Sparta, who had status in society, between slaves and free people. According to some ancient chroniclers, they were slaves, while according to some other chroniclers, they were among slaves and free people. The helots dealt with agriculture and were an important economic factor in Sparta because they provided unhindered conditions for the Spartans to conduct military training to focus on war targets, as it was the main preoccupation for the Spartans. Helots worked at that time to provide food and everything else needed.

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uncle sam would be tossing and turning in his grave : *)