Who did the israelites fight in their first battle after they left egypt?

Amalek

Explanation:

After the Israelites managed to leave Egypt, they continued on their way to the Promised Land. The Amalekites heard of the defeat of Egypt, and they thought that they will have the Isrealites as an prey. The Amalekites attacked the Israelites without any provocation. The Israelites managed to defend themselves, and there were numerous other battles between these two groups of people over the next several hundred years. This battle is described in the battle, where it also says that Yahweh appeared and told the Israelites to fight, and that eventually they will make peace with their enemies.