Simplify the following text for a Grade 8 native English-speaking person.
Original: Narseh did not advance from Armenia and Mesopotamia , leaving Galerius to lead the offensive in 298 with an attack on northern Mesopotamia via Armenia .
Simplified: In 298 Galerius got reinforcements from the Danube in the Spring . He led the army to attack Narseh in northern Mesopotamia , and Narseh retreated to Armenia .