These dogs were developed in England about 100 years ago and are closely related to their even smaller relation the King Charles Spaniels (known in the United States of America as "Toy Spaniels"). One of the main people involved in creating this breed was the British general and politician John Churchill, 1st Duke of Marlborough. They were developed to resemble dogs that were kept as pets and hunting dogs by many members of the royal family in England during the 16th century. King Charles II liked that breed, so this is how the dog was named.