In ancient literature, heroic verse was synonymous with the dactylic hexameter. It was in this measure that those typically heroic poems, the Iliad and Odyssey and the Aeneid were written. In English, however, it was not enough to designate a single iambic line of five beats as heroic verse, because it was necessary to distinguish blank verse from the distich, which was formed by the heroic couplet. This had escaped the notice of Dryden, when he wrote "The English Verse, which we call Heroic, consists of no more than ten syllables." If that were the case, then Paradise Lost would be written in heroic verse, which is not true. What Dryden should have said is "consists of two rhymed lines, each of ten syllables."
In French the alexandrine has always been regarded as the heroic measure of that language. The dactylic movement of the heroic line in ancient Greek, the famous AvBbr rtpg5os of Homer, is expressed in modern Europe by the iambic movement. The consequence is that much of the rush and energy of the antique verse, which at vigorous moments was like the charge of a battalion, is lost. It is owing to this, in part, that the heroic couplet is so often required to give, in translation, the full value of a single Homeric hexameter.
It is important to insist that it is the couplet, not the single line, which constitutes heroic verse. It is interesting to note that the Latin poet Ennius, as reported by Cicero, called the heroic metre of one line versum longum, to distinguish it from the brevity of lyrical measures.
The current form of English heroic verse appears to be the invention of Chaucer, who used it in his Legend of Good Women and afterwards, with still greater freedom, in the Canterbury Tales. Here is an example of it in its earliest development:
In the earlier half of the 17th century, heroic verse was often put to somewhat unheroic purposes, mainly in prologues and epilogues, or other short poems of occasion; but it was nobly redeemed by Marlowe in his Hero and Leander and respectably by Browne in his Britannia's Pastorals. Those Elizabethans who, like Chapman, Warner and Drayton, aimed at producing a warlike and Homeric effect, however, did so in shambling fourteen-syllable couplets. The one heroic poem of that age written at considerable length in the appropriate national metre is the Bosworth Field of Sir John Beaumont (1582-1628).
Since the middle of the 17th century, when heroic verse became the typical and for a while almost the solitary form in which serious English poetry was written, its history has known many vicissitudes. After having been the principal instrument of Dryden and Pope, it was almost entirely rejected by Wordsworth and Coleridge, but revised, with various modifications, by Byron, Shelley (in Julian and Maddalo) and Keats (in Lamia). In the second half of the 19th century its prestige was restored by the brilliant work of Swinburne in Tristram and elsewhere.