Original: From 1908 to 1911 he was the principal conductor of the Vienna Hofoper succeeding Gustav Mahler; he retained the conductorship of the Vienna Philharmonic until 1927.
Simplified: From 1908 to 1911 he was the main conductor of the Vienna Hofoper, following on from Gustav Mahler. He kept the job of conductor of the Vienna Philharmonic until 1927.