Perhaps we should start with what makes a spaniel a spaniel. The easiest answer would be spaniels were traditionally bred and trained to flush prey for hunters, but small companion dogs have also existed for just as long which are clearly spaniels. These dogs all share the same root ancestry and appearance, but their actual origin is unknown. Most scholars point to Spain, from the French word epagneul, but other theories involving Romans and Celts also exist.
Due to the size of this question we will explore this family grouping in separate posts through over several days by looking at the early spaniels decedents both through type (appearance) as well as function. To simplify we have divided the spaniels into four groups: flushing, companion, non-flushing, and water.
This specific post will explore the “true” spaniels – those that were specifically developed for flushing. There are seven breeds in this grouping, five of which hail from England. Each of these dogs descends directly from the early land spaniels and includes the English and Welsh Springers, English and American Cockers, Clumber, Sussex, and Field.
These dogs are a tight grouping, beginning with the English Springer and English Cocker. These two were once so closely related that they were considered the same breed, separated only by size. Larger dogs were destined to become Springing Spaniels (also known at the time as Hawking or Starter) while their smaller littermates became Cocking Spaniels. It wasn't until the late 1800s that attempts were formally made to separate the two sizes.
The English Cocker would also lead directly to the development of the Field Spaniel (due to breeders wanting a solid and slightly larger spaniel) and the American Cocker in the United States. The American Cocker is the only dog in this group that developed away from a hunting breed to become solely used as an companion. It was separated from the English Cocker by the American Kennel Club (AKC) in 1946. Ironically both of these dogs are known simply as 'Cocker Spaniel' in it's homeland, while the foreign cousin is give the title American or English.
It is believed the Sussex and Clumber were created from crosses with the English Springer and hounds (the Clumber's hound addition being French rather than English). Both of these breeds came close to extinction after WWII and although they were saved their numbers have never truly recovered. Both are listed in their homeland as Vulnerable Native Breeds by the Kennel Club (KC) and the Sussex has been in the bottom ten of AKC registrations for several years.
The only dog that may or not share these close relations is the Welsh Springer, which many experts believe to be older than the English breeds. It is mentioned in texts dating from the early 10th century, long before any documentation of spaniels in England.