From 1930 to 1934, Prételat was a general officer commanding France's 2nd Military Region. In 1934, he began five years as a member of France's Supreme War Council. As commander-designate of the Second French Army, in 1938 he conducted exercises exactly paralleling the May 1940 German attack, which revealed that the Ardennes were then virtually indefensible. After the Munich Conference, in December 1938 Prételat issued a report warning that defensive fortifications in the northeast were inadequate. Four months later, he was asked to draw up a plan to improve the fortifications, although when war began in September 1939, little had been done to implement this.
In early September 1939, Prételat was one of two outright opponents of war on the 19-man war council. To demonstrate French support for Poland, as commander of the French Second Army Group, on 8 September he launched a halfhearted offensive against the German Siegfried Line in the Saar region. Prételat believed he possessed inadequate air support for such an undertaking and, with Poland collapsing, French chief of staff Maurice Gamelin ordered it halted on 12 September. When Poland capitulated, Prételat pulled his troops back behind the Maginot Line.
When German forces invaded on 10 May 1940, Prételat's 2nd Army Group forces played little part in the initial fighting, sheltering behind the Maginot Line. Historians later alleged that, in comparison with French units facing the brunt of the German attack, Prételat's sector was grossly overmanned. However, over two weeks, he released 20 of his 30 divisions to reinforce units facing the German assault in the northwest. By 26 May, Prételat, conscious that the 1st and 4th Army Groups to his west were flagging, feared the Germans would turn his left flank and sought permission to abandon the Maginot Line and retreat, but this was refused. Only on 12 June, as a military debacle approached, was he ordered to withdraw. Despite his continuing desperate resistance, within a week German forces encircled the battered remnants of 2nd Army Group, many of whose troops only ceased fighting several days after France accepted German armistice terms on 22 June. An embittered Prételat took no further part in the war. He died in 1969.
Crémieux-Brilhac, Jean-Louis. Les Français de l'an 40. 2 vols. Paris: Gallimard, 1990.; Draper, Theodore. The Six Weeks' War: France May 10–June 25, 1940. New York: Viking, 1964.; Horne, Alistair. To Lose a Battle: France 1940. Boston: Little, Brown, 1969.; Rowe, Vivian. The Great Wall of France: The Triumph of the Maginot Line. London: G. P. Putnam, 1959.; Truscott, Lucian K., Jr. The Twilight of the U.S. Cavalry: Life in the Old Army, 1917–1942. Edited and with Preface by Lucian K. Truscott III and Foreword by Edward M. Coffman. Lawrence: University Press of Kansas, 1989.