Willem Mengelberg succeeded Kes as principal conductor in 1895. During the fifty years that he held the baton in front of the Concertgebouw Orchestra, strong bonds were formed with a wide variety of composers such as Richard Strauss, Mahler, Ravel, Debussy, Stravinksy, Schönberg, Schreker and Milhaud, all of whom conducted the Concertgebouw Orchestra more than once.
The appointment of Willem Mengelberg marked the international breakthrough of the Concertgebouw Orchestra. His musicality and expertise are still a source of inspiration to many composers right up to this day.
Willem Mengelberg was forced to take his leave from the orchestra when he was dismissed in 1945 owing to his compliant attitude during the war years.