A Sign is determined by its Object even when, ‘as not infrequently happens, the Object is brought into existence by the Sign’ (Peirce, EP2:493).
The Object of the sentence “Hamlet was insane” is the Universe of Shakespeare’s Creation so far as it is determined by Hamlet being a part of it. The Object of the Command “Ground arms!” is the immediately subsequent action of the soldiers so far as it is affected by the molition expressed in the command. It cannot be understood unless collateral observation shows the speaker’s relation to the rank of soldiers. You may say, if you like, that the Object is in the Universe of things desired by the Commanding Captain at that moment. Or since the obedience is fully expected, it is in the Universe of his expectation. At any rate, it determines the Sign although it is to be created by the Sign by the circumstance that its Universe is relative to the momentary state of mind of the officer.
EP2:493
The Command is a Sign whose dynamic interpretant is the action of the soldiers, which is determined by ‘the molition expressed in the command.’ Molition is Peirce’s term for ‘volition minus all desire and purpose, the mere consciousness of exertion of any kind’ (CP 8.303, 1909). The officer was conscious of the exertion which he expected, and it was the object of his attention which determined what sign he would utter in order to bring that object into the Universe of actuality.