Complex sentence: Bache's major accomplishment was the establishment of Liszt's music in England at the height of the War of the Romantics, when conservative and liberal musical factions openly argued about the future of classical music and the merits of the compositions written in their respective schools.
Split into simpler sentences: Bache's major accomplishment was the establishment of Liszt's music in England. This was at the height of the War of the Romantics, when conservative and liberal musical factions openly argued about the future of classical music and the merits of the compositions written in their respective schools.