The trip to Jerusalem was Heraclius’s last moment of glory. He fell ill soon afterward; and in the field in the 630s he was represented by other generals, who saw his most important frontiers collapse.
The future lay to the south. Muhammad died in 632, leaving behind a whirlwind prepared to move north, east, and west. The pummeling that Byzantine and Persian forces gave each other and the relative detachment of Syria, Palestine, and Egypt from Byzantine control gave the men of the desert their chance. Just as the northern barbarians had found their strength shadowing the empire they admired, so the Arabs of the desert marches had grown in strength and confidence and were prepared to seize an opportunity. If it was not divine providence that brought them to this moment, they seized it as though it were.
Defeated Theodore
In 634 the Arab armies invaded Syria and defeated Theodore, the emperor’s brother, in a string of battles. Heraclius raised a large army that attacked the Arabs near the Yarmuk River, a tributary of the Jordan, in the fall of 636. After a successful beginning, the larger Byzantine army was defeated and put to flight. Roman Syria was easily taken at that point. The Arabs capitalized on Persia’s disarray by quickly taking the whole of the frontier lands (including Mesopotamia and Armenia) and then Egypt not long afterward. Alexandria fell in 640 after a siege that lasted more than a year. At that time, Muhammad had been dead less than a decade.
What was left for ancient empire? The Balkans, the suburbs of Constantinople, most of Asia Minor, and the African outpost around Carthage that Justinian had seized at such cost. Italy remained, with as much cost as benefit, but the African base would support Constantinople for the sixty years remaining before the Arabs seized it at the turn of the eighth century. (Sicily remained Byzantine much longer: without it, the whole of Byzantine pretension might have fallen.) By the end of the seventh century, the economics of empire had caught up with Constantinople and the city population collapsed.
Heraclius died on February 11, 641, his empire fully and finally in tatters. His two sons failed to establish themselves, and it was his grandson Constans II who became emperor later that year at age eleven, at the onset of what would be a long and pointless reign. Irony alone would accompany him as he visited Rome in 663, the first emperor seen there in two centuries. He was assassinated in his bath in 668, and his successors forgot the west.
Ottoman in Bulgaria 