Complex sentence: The orders were a disappointment to Agesilaus, who had looked forward to further successful campaigning in Asia, but he set out for home with his troops, crossing the Hellespont and marching west through Thrace.
Split into simpler sentences: The orders were a disappointment to Agesilaus, who had looked forward to further successful campaigning. Thus, he turned back with his troops, crossing the Hellespont and marching west through Thrace.