However, Julian lacked the equipment to lay siege to the strongly fortified Ctesiphon, and the main Sassanid army, commanded by Shapur and far larger than the one just defeated, was closing in quickly. Also critical was the failure of Procopius to arrive with the 18,000 detachment of the Roman army that could have aided Julian in crushing Shapur's approaching force as he had intended. For as previously captured satraps had testified after being fairly treated by Julian, the capture or death of Shapur would have compelled the Persian city to open its gates to the new Roman conqueror.