The essential oneness of the army, based on the sultan’s ownership of the standing body of cavalry and infantry and its attachment to his person,[394] and on the incapacity of the territorial armies to carry on great campaigns alone, was also a fact injurious to the Ottoman power. At the accession of Selim I, the empire had been nearly identical in territory with the Byzantine Empire under the Macedonian dynasty. No great power had marched with it. The conquests of Selim in the East and of Suleiman in Hungary had pushed the frontiers to the borders of two great powers: Persia on the east and Austria on the west remained henceforth constantly hostile in feeling and often hostile in fact to the Ottoman Empire.[395] They were so far away from the Ottoman capital that the road to either was a journey of months for the army, and relations with both were often disturbed at the same time; but there was only one great army, and there could be only one serious war. If, while war was in progress on one frontier, conditions became intolerable on the other, it was necessary to make peace on what terms could be had, and carry the army to the other extremity of the empire. Thus, Suleiman and Ibrahim concluded the peace of 1533 with Charles and Ferdinand, in order to be free to proceed against Persia at once;[396] and thus Suleiman was obliged to arrange terms with Ferdinand in 1547, in order to march against Persia in 1548.[397] Had a Cardinal Cesarini absolved Charles and Ferdinand from either treaty, and had they been able to act, they could have marched to Constantinople in 1534, 1535, or 1548 against practically no resistance.[398] On the other hand, had the Ottoman standing army been divisible, and separable from the person of the monarch, the Sultan could have kept a steady pressure at both frontiers; and by taking advantage of opportunities he might have conquered far to the west and north, and realized his ambition of adding all the heretical Persian dominions to his empire so as to reach the Chinese frontier, and of sending the horsetail standards to the Atlantic shore of North Africa.[399] Or he might have carried out the intention expressed through Ibrahim in 1533—which was quite in keeping with his character—of aiding the Emperor Charles V to enforce unity of religious belief upon the Protestants and the pope.[400] It is interesting to notice that Austria possessed two great advantages over Persia in the wars with Turkey. The Ottomans did not wish to pass the winter in the cold north, but they did not object seriously to staying in Aleppo or Bagdad. This attitude probably saved Vienna for Austria and lost Bagdad for Persia. Again, since the journey from Vienna to Constantinople was much easier than that from Tabriz to Constantinople, the Austrians could have reached Constantinople while the Ottoman army was in the East, whereas the Persians could not have reached Constantinople while the Ottomans were in Austria. This advantage