A disagreement between Parker and Nelson saw Nelson's proposal for a pre-emptive show of force overruled and the demands made by a single frigate; the Danish refused to negotiate. The Danish had prepared for the attack and placed a line of defensive blocking ships along the western side of the harbour.
The Copenhagen harbour was both treacherous, and well-defended. With 12 of ships with the least draft, Nelson picked a way through the harbour and commenced action the morning immediately after negotiations had broken down.
For over four hours, the battle was a close run affair with three British vessels stuck on sandbars. At one point three hours into the battle, Parker signalled to Nelson to disengage, but Nelson ignored the signal. It was on this occasion that Nelson is said to have put his telescope to his blind eye, and maintained he could not read the signal.
Eventually, following an extensive shelling of harbour and nearby buildings, Nelson offered surrender terms to which the Danish agreed.