A rare eyewitness account by one of the British heroes of the Battle of Rorke's Drift is to go under the hammer in Devizes more than 100 years later.

Walter Dunne's letter dated January 24 1879, will go on sale at auctioneers Henry Aldridge and Son on Saturday.

It 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 and Stanley Baker.

The letter reveals how, together with a comrade, he fortified the mission station by organising a makeshift barricade from 200lb (91kg) mealie bags which were stacked 5ft (1.5m) 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.

ACO Dunne, who was in charge of the stores at Rorke's Drift, praises Lieutenant Gonville Bromhead, who commanded the 2nd Battalion of the 24th Foot, and was awarded the VC for his part in the battle.

The letter will go under the hammer at auctioneers Henry Aldridge and Son in Devizes, Wiltshire, on November 15 and 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 Bromhead - played by Caine in the famous film - and Lieutenant Colonel Anthony Durnford, who was killed at Isandlwana.

ACO Dunne wrote: "About 1,000 of them came in here and attacked us on the same day. We had got about two hours' notice and fortified the place with bags of grain and biscuit boxes.

"They came on most determinedly (sic) on all sides. They drove our fellows out of the hospital, killed the patients and burned the place.

"They made several attempts to storm us but the soldiers (B Co of 24th under Bromhead) kept up such a steady killing fire that they were driven back each time.

"We had only 80 men, the contingent having bolted before a shot was fired. The fight was kept up all night and in the morning the kafirs retreated leaving 351 dead bodies.

"Dalton was wounded in the shoulder and temp clerk Byrne killed."

The British casualties were nearly double the amount ACO Dunne stated and they faced four times the number of Zulus he estimated.

Heavily outnumbered, the tiny British garrison of some 150 men - many of them sick and wounded - fought for at least 12 hours to repel repeated attacks by up to 4,000 Zulus.

After fighting day and night, the Zulus eventually retreated after 351 of the men died and 500 were wounded.

The defence of Rorke's Drift was recognised with the awarding of no fewer than 11 Victoria Crosses.

ACO Dunne, from County Cork, was turned down for a VC but was mentioned in dispatches.

After 35 years of service, he retired to Gibraltar in 1908 but died the same year at a nursing home.

Auctioneer Andrew Aldridge said: "Generally speaking, anything from the battle is rare. We regularly handle fascinating documents from major historical events but 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.

"It gives us a fascinating snapshot into the events that unfolded at Rorke's Drift written by a man whose bravery was such he was recommended to be awarded the Victoria Cross."

The letter reads: "Rorke's Drift/ 24 Jan.r '79/ My dear Warneford, Sad news about the 1/24th. (1st Battalion, 24th Foot) 5Cd commanded by Col. Pulleine were cut to pieces and the camp sacked. 20 Officers are missing. About 1000 of the Kafirs came in here and attacked us on the same day (22nd).

"We had got about 2 hours notice and fortified the place with trap of grain biscuit boxes &c. They came on most determinedly on all sides. They drove our fellows out of the Hospital, killed the patients and burned the place.

"They made several attempts to storm us but the soldiers (B Co of 24th under Bromhead) kept up such a steady killing fire that they were driven back each time. We had only 80 men, the contingent having bolted before a shot was fired.

"The fight was kept up all night & in the morning the Kafirs retreated leaving 351 dead bodies. Dalton was wounded in the shoulder and temp clerk Byrne killed & 12 of the men... (over) Some of the missing are Pulleine, Col. Dunford, Capt. Russell, Hodson (killed), Anstey, Daly, Mostyn, Dyer, Griffith, Pope, Austin, Pulleine

"(2 Mr.) Shepherd (S... major) Wardell (killed), Younghusband, Degacher, Porteous, Carage Dyson, Atkinson - Coghill is believed to have escaped & also Melvill."