From the same Wiki paragraph,
"At one time Clark claimed that Liddell Hart had given him the quote (unlikely as Hart had asked him where it came from) and Clark's biographer believes he invented the Ludendorff-Hoffmann attribution.[8] This invention has provided a major opportunity for critics of "The Donkeys" to condemn the work. Richard Holmes, wrote of The Donkeys "..it contained a streak of casual dishonesty. Its title is based on the 'Lions led by Donkeys' conversation between Hindenburg [sic] and Ludendorff. There is no evidence whatever for this: none. Not a jot or scintilla. Liddell Hart, who had vetted Clark's manuscript, ought to have known it."[9]"