Marguerite Henry wrote over 50 books about the animals that fascinated her:  dogs and foxes as well as horses, but it is for her pony books that she is best known.  Her Misty series, based on incidents that happened to her and her husband on the island of Chincoteague, where they lived, made the Chincoteague Pony famous.

She had a very restricted childhood, being confined to bed from the ages of 6 to 12 because of rheumatic fever.  There were several books before Misty, which came about after her editor went to the Pony Penning, and suggested she write about it.  When she visited Chincoteague, she met the Beebe family, who feature in the books.

Her historical books are excellent: she wrote about the genesis of the Morgan (Justin Morgan Had A Horse) and the Thoroughbred (King of the Wind).  This historical perspective is rare in pony books, and it is a genre that can deliver historical detail, but flat characters.  The Pullein-Thompson’s Black Beauty’s Family series, though meticulously researched, does not have the immediacy of their other books.  Marguerite Henry’s horses are “objectively portrayed but with character” (James E Higgins) and her humans are vivid too.  Her books are undoubtedly romantic:  there does not seem to be any evidence of Sham’s career as a bakery horse, and his ownership in England isn’t quite as depicted in the books, but they are excellent stories,

She has a knack of making the past seem immediate and involving,

The Misty books, and many of her others, were beautifully illustrated by Wesley Dennis.  The books kept their illustrations in the Armada reprints, though lost their original covers.  I still like the Armada reprint covers of the early 1970s, but the original hardbacks have a charm all their own.  The books are mostly easy to find in the USA - either ebay or abe are good sources.  If you want the original hardbacks, try and go for first or early editions, or check that the one you’re buying has the colour plates.  The early editions have colour plates and colour endpapers but later ones were done in black and white.  I spent an anxious few days after I bought my own King of the Wind  waiting for it to cross the Atlantic, as I bought it before I found about the early editions, but all was well, and it is the most lovely book.   

Sources:
J Murray: Marguerite Henry