The Templars in Historical period would not have surrendered as they were never allowed to be ransomed.
(It was against their code.)
So they only had two options left, Execution, or Slavery.
A Templar would always choose to be executed because it would bring them into heaven with our Lord.
So death awaited them either way.
Many Muslim chroniclers tell of the Templars being executed with smiles on their faces.
They were not ever afraid to die.
SO,
The Templars would die with honor!
And they would never do such a thing as surrender.