"Lions led by donkeys" first occurs in The Times, in the form "Lions led by packasses", in 1871, referring to the French troops defeated by the Prussians . In the present form, it has been attributed to Max Hoffmann (1869-1927), referring to British troops in the Great War, but no confirmation of this attribution has been found [Oxford Dictionary of Quotations, 7th Edition, page 535 at 12 ]
And "contemptible little army" comes from "Exterminate...the treacherous English, walk over General French's contemptible little army". This was said by Kaiser Willhelm II, "the Kaiser", in the Great War, as part of his war orders. Unfortunately, research reveals it to have been probably fabricated by the British.[Same source] Never mind, the troops believed he'd said it, so that's all that matters!