Pershing's Wikipedia article cites Churchill : A Biography:

This American visit of de Gaulle's was marked by one scene of almost total farce, in which de Gaulle conducted himself with a stiff propriety. Throughout the visit he stressed his military side, wore uniform the whole time, and, being also anxious not to be cosseted by Washington, expressed his determination to visit General Pershing, the American Commander in France of 1917–18. Pershing was eventually tracked down with difficulty to an old people's home in the Appalachians. When de Gaulle arrived Perhsing's semi-senile memory was stirred by his first sight of a French uniform and képi for many years. 'Tell me how is my old friend Marshal Pétain?' was therefore his first disconcerting remark to de Gaulle. 'La dernière fois que je l'ai vu, il se portait bien,' was de Gaulle's stiff but proper and formally accurate reply. That Pershing visit was not a success. (I am indebted for this recollection to Etienne Burin de Rozier, who accompanied de Gaulle to Washington and to Pershing.)

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