Dogs of similar size and purpose to the modern beagle can be traced in Ancient Greece back to around the 5th century BC. Xenophon, born around 430 BC, in his Treatise on Hunting or Cynegeticus refers to a hound that hunted hares by scent and was followed on foot. Small hounds are mentioned in the Forest Laws of Canute which exempted them from the ordinance which commanded that all dogs capable of running down a stag should have one foot mutilated. If genuine, these laws would confirm that beagle-type dogs were present in England before 1016, but it is likely the laws were written in the Middle Ages to give a sense of antiquity and tradition to Forest Law. In the 11th century, William the Conqueror brought the Talbot hound to Britain. The Talbot was a predominantly white, slow, deep-throated, scent hound derived from the St. Hubert Hound which had been developed in the 8th century. At some point the English Talbots were crossed with Greyhounds to give them an extra turn of speed. Long extinct, the Talbot strain probably gave rise to the Southern Hound which, in turn, is thought to be an ancestor of the modern-day beagle.
By the 18th century two breeds had been developed for hunting hare and rabbit: the Southern Hound and the North Country Beagle (or Northern Hound). The Southern Hound, a tall, heavy dog with a square head, and long, soft ears, was common from south of the River Trent and probably closely related to the Talbot Hound. Though slow, it had stamina and an excellent scenting ability. The North Country Beagle, possibly a cross between an offshoot of the Talbot stock and a Greyhound, was bred chiefly in Yorkshire and was common in the northern counties. It was smaller than the Southern Hound, less heavy-set and with a more pointed muzzle. It was faster than its southern counterpart but its scenting abilities were less well developed. As fox hunting became increasingly popular, numbers of both types of hound diminished. The beagle-type dogs were crossed with larger breeds such as Stag Hounds to produce the modern Foxhound. The beagle-size varieties came close to extinction but some farmers in the South ensured the survival of the prototype breeds by maintaining small rabbit-hunting packs.
Reverend Phillip Honeywood established a beagle pack in Essex in the 1830s and it is believed that this pack formed the basis for the modern breed. Although details of the pack's lineage are not recorded it is thought that North Country Beagles and Southern Hounds were strongly represented; William Youatt suspected that Harriers formed a good majority of the beagle's bloodline, but the origin of the Harrier is itself obscure. Honeywood's Beagles were small, standing at about 10 inches (25 cm) at the shoulder, and pure white according to John Mills (writing in The Sportsman's Library in 1845). Prince Albert and Lord Winterton also had Beagle packs around this time, and royal favour no doubt led to some revival of interest in the breed, but Honeywood's pack was regarded as the finest of the three.
By 1887 the threat of extinction was on the wane: there were 18 beagle packs in England. The Beagle Club was formed in 1890 and the first standard drawn up at the same time. The following year the Association of Masters of Harriers and Beagles was formed. Both organisations aimed to further the best interests of the breed, and both were keen to produce a standard type of beagle. By 1902, the number of packs had risen to 44.