The three armies of Severus suffered not indeed equally, but still in every case considerably, from three distinct causes--sickness, severe weather, and marked inferiority to the enemy.

The last-named cause had annihilated the southern division; the northern had succumbed to climate; the main army, led by Severus himself, was (comparatively speaking) intact, but even this had been decimated by sickness, and was not in a condition to carry on the war with vigor.

The result of the campaign had thus been altogether favorable to the Persians, but yet it had convinced Artaxerxes that Rome was more powerful than he had thought.

It had shown him that in imagining the time had arrived when they might be easily driven out of Asia--he had made a mistake.

The imperial power had proved itself strong enough to penetrate deeply within his territory, to ravage some of his best provinces, and to threaten his capital.