It's just after Easter and Ottoman Sultan Mehmed II arrives at Constantinople with his armies. His 80,000 soldiers will begin a siege against Constantinople's 7,000 defenders in just four days. The plan is to assault the Theodosian Walls that stretch along the western side of Constantinople, the only part of the city not protected by water.
Mehmed II will be successful in his siege of the city largely because of the acquisition of over sixty artillery pieces, making the siege one of the first successful uses of gunpowder in this fashion. Use of this artillery is improved with the help of gunnery experts sent by Hungarian national hero John Hunyadi who is eager to end the heresy of Eastern Orthodox Christianity, even if it means helping the hated Turks.