Here is what he had to say about the Boers on the very first paragraph of the first page of Chapter One of "The Great Boer War" which is available for download, free, on the Gutenberg Project. I have made it into three chapters for easy reading
Take a community of Dutchmen of the type of those who defended themselves for fifty years against all the power of Spain at a time when Spain was the greatest power in the world. Intermix with them a strain of those inflexible French Huguenots who gave up home and fortune and left their country for ever at the time of the revocation of the Edict of Nantes.
The product must obviously be one of the most rugged, virile, unconquerable races ever seen upon earth. Take this formidable people and train them for seven generations in constant warfare against savage men and ferocious beasts, in circumstances under which no weakling could survive, place them so that they acquire exceptional skill with weapons and in horsemanship, give them a country which is eminently suited to the tactics of the huntsman, the marksman, and the rider.
Then, finally, put a finer temper upon their military qualities by a dour fatalistic Old Testament religion and an ardent and consuming patriotism. Combine all these qualities and all these impulses in one individual, and you have the modern Boer—the most formidable antagonist who ever crossed the path of Imperial Britain. Our military history has largely consisted in our conflicts with France, but Napoleon and all his veterans have never treated us so roughly as these hard-bitten farmers with their ancient theology and their inconveniently modern rifles.
Sir Arthur Conan Doyle.
And now for the Video, enjoy!