Complex sentence: In 1918, the last year of the First World War (1914--18), the Sunday Circle became divided, and they dissolved the salon because of their divergent politics; although several of the leading members accompanied Lukács to the Communist Party of Hungary.
Split into simpler sentences: In 1918, the last year of the First World War (1914--18), the Sunday Circle became divided. They dissolved the salon because of their divergent politics; several of the leading members accompanied Lukács into the Communist Party of Hungary.