Upon his release from the Nazi camp, Martinon became conductor of the Bordeaux Symphony Orchestra (from 1943 to 1945) and assistant conductor of the Paris Conservatory Orchestra
(from 1944 to 1946), then associate conductor of the London Philharmonic
(from 1947 to 1949). He toured as a guest conductor as well, although his U.S. debut did not come until 1957, with the Boston Symphony
giving the American premiere of his Symphony No. 2. Although he devoted as much time as he could to composing in the early postwar years -- producing a string quartet (1946), an "Irish" Symphony (1948), the ballet Ambohimanga (1946), and the opera Hécube (1949-1954) -- he was increasingly occupied with conducting, working with the Concerts Lamoureux (from 1951 to 1957), the Israel Philharmonic (from 1957 to 1959), and Düsseldorf Symphony Orchestra (from 1960 to 1966). In 1963, he succeeded Fritz Reiner
as head of the Chicago Symphony. Martinon's tenure there was difficult. In five seasons, he conducted 60 works by modern European and American composers, and made a number of outstanding LPs for RCA, mostly of bracing twentieth century repertory in audiophile sound. Chicago's conservative music lovers soon sent him packing.
Martinon jumped at the chance to take over the French National Radio Orchestra in 1968; working with this ensemble, he recorded almost the entire standard French repertory for Erato and EMI. His earlier Erato efforts that focused on such secondary but nevertheless interesting figures as Roussel, Pierné, and Dukas
, whereas EMI assigned him integral sets of the Saint-Saëns
symphonies and the orchestral works of Debussy
, among other projects. In 1974, he was appointed principal conductor of the Residentie Orkest in The Hague, but he died before that relationship could bear much fruit.
Martinon resumed his career as a composer around 1960, writing his Violin Concerto No. 2 (1960) for Henryk Szeryng
, his Cello Concerto (1964) for Pierre Fournier
, and his Symphony No. 4 ("Altitudes"), composed in 1965, for the 75th anniversary of the Chicago Symphony. He acknowledged Prokofiev
as strong influences on his scores, which meld Expressionism with French Neoclassicism. Martinon continued composing into the 1970s, but he seldom recorded any of his own music, with the notable exceptions of the Second Symphony, "Hymne à la vie" (ORTF, for Barclay Inedits) and Fourth Symphony, "Altitudes" (Chicago SO, for RCA).