Conversation so far:
What can you tell me about this?
After 35 years of loyal service, d'Artagnan resigns as lieutenant of the Musketeers as he perceives the young king Louis XIV as weak-willed.
Why would that make him resign?
CANNOTANSWER.
What happened next?
He resolves to aid the exiled Charles II to retake the throne of England, unaware that Athos is attempting the same.

Question: How does he help Charles?
Self-contained rewrite: How does d'Artagnan help Charles?