Turn a blind eye

The idiom to turn a blind eye is used to describe the process of ignoring unpopular orders, or inconvenient facts or activities.

The phrase turn a blind eye is attributed to an incident in the life of Admiral Horatio Nelson.

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.