Turn a blind eye
Nelson was blinded in one eye earlier in his Royal Navy career. During the Battle of Copenhagen cautious Admiral Sir Hyde Parker, in overall command of the British forces, ordered Nelson's forces to withdraw. Naval orders were transmitted via a system of signal flags at that time. And when this order was drawn to the more aggressive Nelson's attention he lifted his telescope up to his blind eye, said he didn't see any signal, and ordered his forces to successfully press home the attack.