They are, properly speaking, heraldic supporters appearing in the full royal coat of arms of the United Kingdom.
The traditional legend of enmity between the two heraldic animals is recorded in a nursery rhyme which has a Roud Folk Song Index number of 20170.
It is usually given with the lyrics: The legend of the two animals may have been intensified by the Acts of Union 1707 and it was one year later that William King (1663–1712) recorded a verse very similar to the first stanza of the modern rhyme.
Carroll subverts the traditional view of a lion being alert and calculating by making this particular one slow and rather stupid, although clearly the better fighter.
Sir John Tenniel's illustrations for the section caricature Benjamin Disraeli as the Unicorn, and William Ewart Gladstone as the Lion, alluding to the pair's frequent parliamentary battles, although there is no evidence that this was Carroll's intention.