Shapur accompanied his father's campaigns against the Parthians, who still controlled much of the Iranian plateau through a system of vassal states, in which the Persian kingdom had itself previously been a part.
Shapur ledsaget sin far i hans kampagner mod partherne, der på det tidspunkt kontrollerede store dele af den Iranske plateau gennem et system af vasalstater som det Persiske rige havde selv tidligere været en del af.