Johannes Grant or Johannis Grandi[1] was a mercenary employed by the Byzantine Empire at the fall of Constantinople in 1453.
Contemporary Greek and Latin accounts referred to him as being German,[2][3] although Runciman has suggested he may actually have been a Scot named John Grant.
[4] He appears to have been affiliated with the Genoese contingent of mercenaries at the siege, possibly part of the men commanded by Giovanni Giustiniani.
He would fill barrels with water and observe the waves, using incendiary weapons, mostly Cheirosiphon to destroy Ottoman tunnels.
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