Amalek
In the Book of Exodus Chapter 17, Amalek’s descendants called the Amalekites attacked  the Israelites after the Israelites left Egypt.  So Moses sent Joshua to fight the Amalekites. As long as Moses held his hands in the air, the Israelites were winning but Moses’s hands got tired so he got his brother Aaron to hold one up while Hur held the other up. And Joshua beat the Amalekites.