Complex sentence: He first achieved literary success through his novels, notably "Siegfried et le Limousin" (1922) and "Eglantine" (1927), but it is his plays that gained him international renown.
Split into simpler sentences: He first achieved literary success through his novels, notably "Siegfried et le Limousin" (1922) and "Eglantine" (1927). But it is his plays that gained him international renown.