"Severus marched on Rome, ousted Julianus, and was proclaimed emperor. He then built himself a strong army that would protect both him and his empire.
As I found from my web search is that "would" could mean ( anyone can correct me here) "used to" thus the sentence could mean that the army used to protect the emperor. ( some armies just used to protect their dictators) The word also could mean "was willing" thus the army was willing to protect the emperor.
Which meaning is correct and how could we know ?