Complex sentence: Witherspoon was opposed to the Jacobite rising of 1745-46 and following the Jacobite victory at the Battle of Falkirk (1746) he was briefly imprisoned at Doune Castle, which had a long-term impact on his health.
Split into simpler sentences: Witherspoon was opposed to the Jacobite rising of 1745-46. Following the Jacobite victory at the Battle of Falkirk (1746), he was briefly imprisoned at Doune Castle, which had a long-term impact on his health.