A rare eyewitness account by one of the British heroes of the Battle of Rorke’s Drift is to go under the hammer at Henry Aldridge & Son in Devizes on Saturday.

Walter Dunne’s letter, dated January 24, 1879, describes how he and a vastly outnumbered group of soldiers successfully defended an outpost in South Africa against 4,000 Zulu warriors.

The Assistant Commissary Officer was recommended for the Victoria Cross for his role in the heroic stand, which was immortalised in the 1964 film Zulu, starring Michael Caine.

The letter reveals how, together with a comrade, he fortified the mission station by organising a makeshift barricade from 200lb mealie bags stacked 5ft high.

The following day, ACO Dunne picked up a delivery note for the mealie bags and used it to write the letter to friend Captain WJ Warneford in Cape Colony in South Africa.

He describes how, after the Zulus killed 1,500 British soldiers of the 1st Battalion, 24th Regiment of Foot at nearby Isandlwana, they headed to the outpost at Rorke’s Drift, quickly surrounding the troops.

The letter is estimated to fetch between £14,000 and £16,000.

It was discovered in an album of letters, paintings and other items collected by Capt Warneford’s wife Winifred.

Also included in the sale are letters from Lt Gonville Bromhead, played by Caine in the film.

The defence of Rorke’s Drift was recognised with the awarding of 11 Victoria Crosses. ACO Dunne, from County Cork, was turned down for a VC but was mentioned in Dispatches.

Auctioneer Andrew Aldridge said: “It is a genuine honour to be selling such an important letter written only a matter of hours after one of the most famous battles in British military history.”