Pierre Laval is remembered today, if at all, for his role as a high official in France's Vichy government during World War II. However, he also was a very prominent politician before the war, serving as foreign minister and prime minister. His behavior in those pre-war roles may give us some clues as to what we may expect from a President Trump. Here is historian Robert Paxton's take:
"Personally, Laval brought to foreign and financial affairs the supreme self-confidence of a self-made man, contempt for the cautious upper-class rituals of professional diplomats and international bankers, techniques of direct bluff talk, and the inveterate fixer's enjoyment of knot-cutting, which had worked so well at Chateldon and Aubervilliers. This political and personal mixture was disastrous. Laval rushed into delicate affairs with inexperienced directness. In 1931 his personal negotiations with German Chancellor Bruning and President Hoover did nothing to stem the world financial crisis or to ease Franco-German relations. In 1935 he seemed to give Mussolini a free hand in Abyssinia, was unable to prevent the storm that followed in French and British public opinion, and managed to antagonize everyone. It is not clear to this day what he told Mussolini. After negotiating a mutual security agreement with Stalin in 1935, he made no effort to have it ratified at home."
This is on pages 27 and 28 of Robert O. Paxton, Vichy France (1972).