Complex sentence: After a brief stay in Frankfurt he returned to Switzerland after the outbreak of the First World War and became President of the High Court of the Saarland in Saarlouis in 1921.
Split into simpler sentences: After a brief stay in Frankfurt he returned to Switzerland after the outbreak of the First World War. Following the war, he became President of the High Court of the Saarland in Saarlouis in 1921.