Constantinople's Strategic Vision

The Bosphorus provided large seasonal catches of tuna and mackerel, and enough sturgeon to make caviar a common food. This meant that fish were plentiful and were a cheap source of food for the population. So with all that in place, all Constantinople needed to become a fortress was large, imposing land walls - and man did they have them. Theodosian walls were built by the Prefect Anthemius in 413, and hastily rebuilt after an earthquake in 447. Any attempt to storm these walls would leave an attacking army with a lot of climbing to do, all the while being fired on from above.