Further, he took up arms and fired at American forces in the performance of their duties.

"And have you ever known me to be drunk in the performance of my duties?"

"Perhaps not so keen in the performance of his duty as he might be?"

They were specifically responsible to the court for the performance of their duties.

One does not thank another for the simple performance of one's duty.

"And I shall die in the performance of my duty."

"Doctor, I would never interfere in the performance of your duty."

Or, another way to look at it, the car was damaged by a police officer in the performance of his duty.

I was being lax in the performance of my duties.

"The only thing they should worry about, Commander, is the performance of their duties."