Some historical information on the fall of Constantinople:

Attackers
Campaign: against Byzantium
Leader: Mahomet the Second
Objective: Wrest control of the cty & thus control the Bosphorus, Destroy the last hold of Byzantium.
Forces Engaged:
-15,000 Yeni Ceri (Janissaries)
-35,000 regulars & mercenaries
-69 Canon

Defenders
Leader: Constantine IX
Forces Engaged:
- 8,900 Regulars & militia

Deciding Moment
800 Yeni Ceri rush a small gate near the St.Romanus gate, and break through to the second wall. The fate of the siege is decided.

Result
The entire garrison of Constantinople was killed or enslaved, Constantine was Killed in H2H

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I guess that picture could be of Constantinople as the final assualt began at 01:30 on 29the May 1453.