Complex sentence: In 173 AD the Quadi rebelled and overthrew Furtius, and replaced him with Ariogaesus, who wanted to enter into negotiations with Marcus, who, as the success of the Marcomannic wars was in no danger, he refused to negotiate.
Split into simpler sentences: In 173 AD the Quadi rebelled and overthrew Furtius, and replaced him with Ariogaesus, who wanted to enter into negotiations with Marcus. As the success of the Marcomannic wars was in no danger, Marcus refused to negotiate.