Constantinople fell 2 important times during the Middle Ages. Once by the Latins of the 4th Crusade, and one last time by the Ottoman Turks.
But why did the 1204 siege of Constantinople by the Latin Crusaders last only 5 days, while the 1453 siege by the Ottomans lasted 53 days, and was much harder for them to succeed? The Ottomans had far superior numbers, were better prepared with far superior technology (like their huge cannons), and the Byzantine Empire was much, much, much, much weaker in all fronts, compared to their 1204 state.
I know the Empire wasn't at its best during that time, and that the Angelos dynasty was beyond useless, having weakened the Empire significantly during the previous decades, but I would assume the Empire would have been much stronger, with more resources and able to deal with a besieging army, compared to the decaying, barely living state it was during the Ottoman times. What am I missing here? Why does the 1204 seige seem so much easier to me?
The styles of siege were far different. While I can't comment extensively on the 1204 siege, the siege ended quickly because the invaders ended the siege by breaching the walls, not because the defenders had been weakened significantly by the siege. It is worth noting that Constantinople had suffered major infrastructural damage in the siege the previous year with fires destroying up to a quarter of the city. Many of the debris and burnt out buildings (along with some wall fortifications) were not sufficiently repaired in a timely manner, and as such during the 1203 siege, the defenders were actually hurling burnt debris at the crusaders.
As for 1453. The sieging tactics were entirely different. Niccolo Barbaro gives us a first person account from inside Constaninople during the siege, in his diary he writes, "..we waited every hour for the Turkish fleet to come to attack us. So each day we were in this difficulty, and in great fear, as I have said previously, having by day and by night to stand to our arms, and yet their fleet never moved, or if a galley did move, it went in the direction of Anatalia, or towards the mouth of the Black Sea, to go to their newly built castle; and their fleet never came to attack us, but made us stand to our arms from fear of them, from the twelfth of April until the twenty-ninth of May, all day and all night." That is 47 days of siting outside Constantinople.
Each night the Ottoman soldiers would scream warcries throughout the night to strike fear into the heart of the defenders. I would hesitate to call it anything so organized as psychological warfare, but nonetheless the Ottomans spent months demoralizing the enemy without making a real attempt at capturing the city. The "large forces" the Ottoman soldiers sent at the walls periodically numbers around 200, even though a conservative estimate of the troops outside the walls numbered between 50,000 and 80,000 men, including the elite Janissary Corps.
It was not until early May that the Ottoman troops began in earnest attempted to break down the walls of the city. Sending 30,000 troops one night to attempt to break down the walls. I won't go into all the siege details, because they are extensive, but there were amazing methods used by the Turks to gain an advantage against the defenders. Using cannons, the Turks would break down portions of the wall and force the defenders to constantly be rebuilding the wall, but still not make the final push for weeks.
What I'm trying to get it as that the main differences between these siege techniques revolved around the fundamental methodology of sieging. While the Crusaders meant to take the city with swift and forceful attacks, the Ottoman empire contented themselves with draining the city of its resources until they felt the time was right to take the city, and when they did make the final push, the battle lasted for a very short period and the takeover completed quickly. To the point Mehmed held prayer in the Hagia Sofia less than a week after the downfall of Constantinople.