Complex sentence: The song is part of the musical testimony to Keel's activity as organizer and chair of the Ruhleben Music Society, consisting of 36 prisoners; the group's concerts were subsequently reported in the Times for 30 January 1919.
Split into simpler sentences: The song is testimony to Keel's activity as organizer and chair of the Ruhleben Music Society, consisting of 36 prisoners. The group's concerts were subsequently reported in the Times for 30 January 1919.