Letters from Navy commander Vice-Admiral Lord Horatio Nelson are expected to fetch up to £6 million at auction.

The historic collection consists of 415 documents, manuscripts and letters relating to the officer, who is renowned for his triumphs over French forces during the Napoleonic Wars.

Described as "the greatest collection of its kind in private hands", the lot features notes sent to his lover, Emma Hamilton, alongside his own accounts of victories and his experience learning to write using his left hand after losing his right arm in battle.

The lot, assembled over a period of 40 years by entrepreneur Clive Richard, went on display at Sotheby’s for the first time on Wednesday to mark the anniversary of the Battle of Trafalgar – a major naval fight led by Nelson – also known as Trafalgar Day.

The lot is estimated to sell for between £4 and £6 million, with the proceeds going to the Clive Richards Foundation, which is committed to supporting education, healthcare, heritage and arts.

Sotheby’s book and manuscript specialist Gabriel Heaton told the Press Association: “This is the greatest collection of its kind in private hands, full-stop.

“We’re really privileged to be presenting here the Clive Richards collection of letters and documents relating to Admiral Nelson, one of the towering figures of British history.

“What we have here is a wonderful collection of hundreds of letters covering every aspect of Nelson’s life and career, and of those closest to him, and those who served alongside him.

“Nelson is such a widely loved and respected figure. There are so many aspects to him that it’s pretty hard to pin him down to just one personal location.”

Dr Heaton said the auction house often sells individual letters and documents by Nelson or Hamilton, however having an entire collection go up for sale was a “truly unique opportunity”.

At the core of the collection is The Nelson Papers, a comprehensive archive of documents by Nelson himself, including 168 autograph letters that shed a light on his life and character.

According to the auction house, the archive also records the personal cost of a life spent at war, with letters written after Nelson lost sight in one eye as well as following the amputation of his right arm.

The lot also includes 24 letters to Hamilton, offering an insight into their love affair which was conducted openly despite them both being married.

In one letter dated January 1800, Nelson recounts a dream he had about Hamilton and his desire to see her again.

co-host Dominic Sandbrook said: “For anybody interested in Nelson, the Royal Navy, the Napoleonic Wars or British history generally, this is an extraordinarily rich and exciting collection.

“Indeed, some of these letters and documents – such as Nelson’s handwritten reports on the battles of the Nile and Copenhagen, or his battle plans for Trafalgar – rank alongside the most sacred texts of our national history.

“Stirring and touching by turns, these are truly wonderful things. If only I had made better decisions when I was young and gone into AI development instead of writing history books, I would be throwing every last penny at this myself.”

The lot also features the Hamilton Papers, which includes 73 letters written by Hamilton herself as well as the Nelson Family papers which traces the wider history of the family and includes letters between his relatives.

Nelson died at the Battle of Trafalgar in 1805 at the age of 47. Numerous monuments, including Nelson’s Column in Trafalgar Square, have been created to honour him.

Bidding opened on Wednesday and will run until 18 November.