Which Ottoman sultan conquered Constantinople in 1453?

Mehmed II, at 21, ending an empire that had lasted in some form for over a thousand years - and he did it with artillery. He commissioned enormous bombards from a Hungarian engineer who had first offered his services to the Byzantines, who could not pay him.

The walls of Constantinople had held for a millennium and were the best fortifications in Europe. Cannon of that size were slow, unreliable and burst frequently, and they still reduced the walls in a way nothing previously could - the siege is a standard marker for the end of the medieval military order, in which a sufficiently good wall was an answer to almost any army.

He also had ships hauled overland. Blocked from the Golden Horn by a chain across its mouth, he had a road of greased logs built and dragged some seventy vessels over a hill into the harbour behind it. After the city fell he styled himself Kayser-i Rum, Caesar of Rome, claimed the imperial succession, and set about repopulating a half-empty city by inviting Greeks, Armenians and Jews back into it - including Jewish communities expelled from Spain forty years later.