Which preposition to use with incompetency

of Occurrences 15%

Jack was filled with dire fears that the commanding officer, having discovered the incompetency of Oswald, feared to take the Caribees to the front.

in Occurrences 2%

well knew that an uprising among the nobles might occur upon any pretext, and no pretext could be so powerful as the suspicion of incompetency in the sovereign.

at Occurrences 1%

Miserable as was the display of military incompetency at Carwar and on subsequent occasions, it is hardly surprising when the condition of the Company's soldiers is considered.

for Occurrences 1%

He exhibited, throughout, an infatuation and a degree of incompetency for great achievements, which would cover the enterprise with ridicule, were it not for the misfortunes which it brought upon himself and others.

Which preposition to use with  incompetency