Which preposition to use with authorisation

of Occurrences 4%

In this month, Mr. Davis appointed as successor to Mann, Mr. Mason of Virginia, to whom was given a more formal authorisation of action.

from Occurrences 1%

And it was no slight proof of his force of character and energy, as well as of his address, that, as the National Guard could not be employed out of the routine of their regular duty without a special authorisation from the civil power, he contrived to extort from Pétion, as mayor of the city, a formal authority to augment his brigade for the special occasion, and, if force should be used against him, to repel it by force.

Which preposition to use with  authorisation