Question

why byzantine empire was most powerful than any other ?

Answer 1

Defending your capital from would-be invaders is a great example of forward thinking. And what better way to do so than by building the largest wall Europe had ever seen? The west end of Constantinople had no natural protection from invasion, so Emperor Constantine the Great started building one in 324 AD. Not even a hundred years later, Constantinople outgrew its boundaries and Emperor Theodosius IIstarted construction on a second wall one mile west of the old one, which spans from the Sea of Marmara to the Golden Horn.

But disaster struck on November 6, 447, when a powerful earthquake destroyed large parts of the wall and none other than Attila the Hun was looking for some easy pickings. Luckily, the urban prefect Kyros of Floras managed to not only rebuild but also add a second outer wall and a moat, and all within 60 days. It was just in time to properly greet poor old Attila, who had to go back to pillaging the rest of Europe. These walls stand to this day as a testament to Byzantine engineering and are known as the Theodosian Walls.

Constantinople also had sea walls that completely surrounded the city. These weren’t as big or as fortified as the main walls, but access to the Golden Horn was restricted by a heavy chain and strong currents on the Marmara coast made an effective attack by a fleet next to impossible.