Why didn the French invade the Channel Islands?
It probably came down to this. Taking them would have been fairly easy, keeping them would have been very hard and or expensive, far too great to justify the costs. In the mid 17th century I think it have been most possible, the French were more centralised and Better run than the English and in the middle of the century the English had a nasty civil war to keep them busy. However there was still a sense of ‘right’ in this period and most accepted it was right for the English King to hold the Channel Islands. There was also the issue of the French having bigger fish to fry being involved openly or not with the 30 years war in Germany and Spain, so they were probably happy that the Channel was a quiet area for them. When the English/British were art war with France in the later period (1700’s onwards) the British generally had control of the seas. Though it would not have been very hard for a French force to get to the Islands once there any troops would likely be cut off. The French wo
