Quotes from Roger Crowley

They had no particular reason to evolve because siege warfare itself remained static. The basic techniques and equipment – blockade, mining, and escalade, the use of battering rams, catapults, towers, tunnels, and ladders – these were largely unchanging for longer than anyone could recall. The advantage always lay with the defender; in the case of Constantinople its coastal position increased that weighting.

On April 12 lighted tapers were put to the touchholes of the sultan's guns along a four-mile sector, and the world's first concerted artillery bombardment exploded into life.