Because of the ambitions of the playwright and the limitations of the Elizabethan stage, an introduction is in order and the Prologue serves as that introduction. Chronologically, this is only the second time in Shakespeare's career that he has used the device of a Chorus to introduce a drama (the first time he used a Chorus, it introduced Romeo and Juliet).
One of Shakespeare's purposes in using the Chorus is to be able to celebrate the greatness of Henry V directly; for that reason, he does not have to rely solely on the other characters to sing the king's praises. The Chorus also sets the time and place for the drama and excites the imagination of the audience. The audience, of course, must use its imagination in any type of drama, but now Shakespeare is demanding that they extend even further their imagination and create large battlefields and countries across the sea and hordes of horses charging up and down the landscape. This demand to the audience is partly an answer to the classicists who complained that Shakespeare took too many liberties with the Elizabethan stage and violated the classical sense of the unities of time and place. It is, nonetheless, effective.
Before each of the subsequent acts, Shakespeare will also use the Chorus as a device to compensate for the limitations of the stage and continually to remind the audience of a need for imaginative cooperation.
