What led to the fall of the Byzantine Empire?

Related questions

1. How many times has Rome been sacked?
2. Why was Byzantium called the new Rome?
3. Why is it called Istanbul?
4. Was the Byzantine empire the Roman Empire?
5. How long did the Byzantines hold Rome?
6. What was Istanbul originally called?
7. Who was the greatest sultan of the Ottoman Empire?
8. Was Byzantine a city?
9. When was the Byzantine Empire most powerful?
10. What countries were part of the Byzantine Empire?

Tags

1. #which
2. #there
3. #pressure
4. #losing
5. #control
6. #crusaders
7. #seljuk
8. #weakened
9. #centuries
10. #turks
11. #minor
12. #after
13. #sacked
14. #constantinople
15. #further
16. #under
17. #byzantines
18. #supposedly
19. #anatolia
20. #empire
21. #however
22. #battle
23. #manzikert