In the conflict between monarchist Britain and revolutionary France Britain was imposing a blockade of France and was stopping and searching the ships of other countries for countermanded material that might be going to France. Russia began organizing a coalition to resist the British search and seizure of their ships. The coalition consisted of Denmark, Sweden and Prussia as well as Russia. In December of 1800 the coalition agreement was signed. The coalition was called The League of Armed Neutrality In March of 1801 Britain sent a major fleet into the Baltic area to break up the coalition.

The British fleet consisted of 53 vessels but only 18 were suitable for the battle line. The Danes had only seven or eight ships suitable for battle, but the Swedes had eleven. The Russians had numerous ships suitable for the battle line but all were too far away and most were locked in by ice. After dealing with the Danes the intention of the British was to sail to Reval (now Tallinin, Estonia) to prevent the Russian fleet there from joining the Russian fleet at Kronstadt near St. Petersburg.

The British sent a representative to deliver an ultimatum to the Danish king: "Either Denmark withdraw from the coalition with Russia, Sweden and Prussia or face attack." The Danish king refused the ultimatum because complying with it could well provoke an attack by Russia. So the British fleet prepared to attack Copenhagen. When the British ships entered the Sound the Danes fired on them. But the shots fell short and the Swedes across the Sound at Malmo did not come to the aid of their coalition partner. So, although the coalition had enough ships to match the British fleet it was only the Danish ships which were going to counter the British.

The British fleet was under the command of Sir Hyde Parker but with Horatio Nelson as his second in command. Nelson was a genius at battle tactics. Copenhagen is a port on the Baltic Sea but it is laid out along the sea channel that runs between the big island of Zealand and the smaller island of Amager. In many ways Copenhagen is more like a river port. Danes had formidable gun emplacements at Tre Kroner (Three Crowns: Denmark, Norway and Sweden) to guard the entry to the channel from the north. Nelson, tactical genius that he was, searched for an entry to the channel from the south. During the night he had soundings taken to the east of the island of Amager. He found there were two parallel channels separated by an area of shoals called the Middle Ground. The channel closest to the island was called the King's Deep. The other channel was the Outer Deep.

Nelson proposed to Parker that he use about half of the fleet and pass around the Middle Ground in the Outer Deep. This would allow his ships to attack the Danish fleet from the south end of the King's Deep and, if successful, bombard Copenhagen from the east. Parker gave him about ten ships, the ones of shallower draft. The Danish battle fleet was stationed along the King's Deep. In addition there were armed hulks included in this line which could not sail. Some were simply floating batteries. Many of the crews manning these hulks had no sailing experience. Nelson's ships passed along the King's Deep with their guns blazing. The British guns and gunnery were superior to those of the Danes. So although the number of British ships in the battle was smaller they were far more effective.

Several Danish ships were soon so damaged that their crew put up a signal that they surrendered and the British stopped firing upon them. Nelson lost three ships due to groundings but he still had about seven battle-ready.

During the battle Parker became worried about the survival of the force under Nelson's command. He sent a messenger by boat to inform Nelson that he could withdraw from the battle if he so chose. Before that messenger could get to Nelson Parker thought the battle was going so badly for Nelson that Parker sent a message by signaling that told Nelson to withdraw. Nelson chose to ignore that signaled order by putting his telescope up to his right eye which had been blinded in a battle with the French in Corsica six years before. The losses were horrific on both sides, but the Danes lost several times as many sailors as what the British lost. The Danes lost more than a dozen ships and the British lost none in the battle, only three to grounding.

During a lull in the battle Nelson's ships attempted to take control of the Danish ships and hulks which had surrendered. When they did so other Danes fired upon them contrary to international convention. Nelson used this violation of the rules of war to open up communication with the Danish authorities. He addressed his message to: the Danes, the brothers of the Englishmen. His message said that if his forces were not allowed to take possession of the surrendered Danish ships he would be forced to burn those ships with the brave Danish sailors on them. This gave the Danish authorities the opportunity to reconsider their rejection of the British demand that Denmark withdraw from the coalition. It was a matter of eminent present defeat versus possible future difficulties with Russia. Nelson went to Copenhagen to carry out the negotiation. During the negotiations he assured the Danes that Britain would provide support for them if any difficulties with the Russians developed. A truce was agreed to that ended the conflict. About two weeks after the battle Hyde Parker was relieved of his command and Nelson was put in control.

As it happened the Russian Czar who had organized the The League of Armed Neutrality was assassinated and his successor was not much interested in pursuing its continuation. Nelson returned to Britain as a national hero.