Why was the name Jehovah-Nissi given?
Jehovah-Nissi, meaning 'our banner,' was given after Israel's first war coming out of Egypt against the Amalekites. When Moses' hands were held up, Israel prevailed, and the name commemorated that Jehovah won the battle for them. It acknowledged Jehovah as the one who secured the victory.
Les explains that Jehovah-Nissi goes back to Israel’s first war after coming out of Egypt, when they ran up against the Amalekites. When Moses held his hands up, the battle went for Israel; when he got tired and his hands fell down, Israel began getting whooped. But his arms were held up, and Israel won the battle. As a result, the name Jehovah was coined Jehovah-Nissi, meaning 'our banner,' because it was Jehovah who won the battle. This is one of the names of deity intrinsic with God’s dealing with Israel, all wrapped up in the one name Jehovah.