Quick breakdown of historical significance of a few of the castles pictured:
Amboise is where da Vinci lived out his final days under patronage of Charles VIII; it is the site of the slaughter of 1,200 Huguenots in 1560, the first royal chateau on the Loire.
Chenonceau, aside from its important WW II role with the French Resistance and as the line of demarcation between occupied and so called free France, it is the castle where the queen mother, Catherine de Medici orchestrated policy against the Huguenots, including the St Bartholemews Day Massacre in 1572 (see the birthday girl standing in Catherine's study).
Chervernay, also with WW II significance in that many of the treasures from the Louvre were hidden here including da Vincis Mona Lisa, has only minimal Huguenot significance, except that my wife really wanted to visit this charming castle and village, and she puts up with heaps from me planning our itinerary around research. We all loved it, especially the TinTin fans amongst us, this castle being the place wher the author of TinTin got his inspiration... Castles are good places for writing inspiration.
Blois is important to Huguenot history. Readers will learn about the arch nemesis of the Huguenots the Guise brothers, orchestrators of several premeditated massacres (Vassy and Sens come immediately to mind) and defiant violators of royal edicts designed to create a modicum of peace and freedom of worship for Huguenots. They were both murdered here, but not by Huguenots, by King Henri III who was fed up with these two trouble makers, always Catherine de Medici behind foul play in France, however.
Montpoupon and another along the Loire, just really cool castles (stopped along the dike in the Loire and stepped out to take this picture, there was a French license plate that had fallen off a car some time before, just what I'd been looking for), and more of "ours", la celle guenand.