Complex sentence: Stephen's son and heir Eustace continued to oppose a settlement with Henry however Eustace died suddenly in August 1153 effectively putting an end to organised resistance to Henry's claim to the throne.
Split into simpler sentences: Stephen's son and heir Eustace continued to oppose a settlement with Henry. However, Eustace died suddenly in August 1153, effectively putting an end to organised resistance to Henry's claim to the throne.