LONDON (Reuters) - A huge archive of letters, papers and photographs that shed new light on Indian leader Mahatma Gandhi and his time in South Africa will be auctioned in London next month and is expected to fetch 500,000-700,000 pounds ($800,000-$1.1 million).
The documents, numbering several thousand and arranged in 18 files, belonged to Hermann Kallenbach, who became arguably Gandhi's closest friend after they met in Johannesburg in 1904.
Although relatively few are in Gandhi's own hand, the wealth of material from family, friends, associates and Kallenbach himself make the collection a key biographical source for one of the 20th century's most revered figures.
"The vast majority of this is unknown and unpublished, and has not been used by scholars in the last generation or two," said Gabriel Heaton, a books and manuscripts specialist at Sotheby's auctioneers which is selling the archive.
"It is very much material that will be adding to our sum knowledge of Gandhi and his life," he told Reuters.
The documents will go under the hammer as a single lot on July 10 at the English Literature and History sale.
Sotheby's also handled the sale in 1986 of the main series of Gandhi's letters to Kallenbach, when they raised 140,000 pounds. Together, the two batches represent the vast majority of the Kallenbach family's Gandhi collection.
"He is one of the towering figures of the 20th century," said Heaton, when asked to explain Gandhi's appeal to collectors and historians.
"There is only a tiny handful of individuals who have had such an enormous effect on world history ... Unlike most other comparable figures he never had an army at his disposal, which makes him unique in that way."
The appetite for Gandhi memorabilia has shown few signs of abating over time.
In one of the more bizarre sales in recent years, samples of soil and blades of bloody grass purportedly from the spot where Gandhi was assassinated in 1948 sold for 10,000 pounds at a British auction in April, while a pair of his glasses fetched 34,000 pounds.
Kallenbach met Gandhi in 1904 in South Africa, where the Indian leader spent more than 20 years of his life before returning to India permanently in 1915.
Gandhi's time in Africa, ostensibly as a lawyer, had a profound influence on his thinking as he joined the struggle to obtain basic rights for Indians living there.
Kallenbach, a German-born Jewish South African, was an architect who fell under the influence of Gandhi and his ideas, and the two men became lifelong friends.
"So many of the letters refer to the importance of this relationship and how Kallenbach was able to support Gandhi in a way few others could," Heaton explained.
He gifted a large piece of land to his mentor which he named Tolstoy Farm, in honor of Russian author and philosopher Leo Tolstoy whose ideal of peaceful resistance influenced Gandhi.
Among the most illuminating of the documents on sale are the dozens of letters written by Gandhi's sons which provide details of Gandhi's life in India, particularly after his return when he lived in relative obscurity.
"Father is becoming more and more awful," read one incomplete letter probably written by Harilal, his eldest.
"It would not be strange if a time may come one of these days when either those who are living with Father might have to go or he might leave us all not being able to stand our life."
Heaton believed Gandhi's family felt able to speak more freely to Kallenbach than just about anyone else.
"They are writing to someone who's essentially a close family friend and also someone they knew understood their father as a man and not just a political head."
Reporting by Mike Collett-White, editing by Paul Casciato