Describe the significance of the invocation of The Faerie Queene?

Conventionally an ancient writer, while commencing an epic poem, invoked the help and the blessings of the Muse of epic poetry. Actually the name of the Muse of epic poetry was Calliope. But Spenser here invokes the help, not of the Muse of epic poetry but of history whose name was Clio. The poet invokes the help of this Muse of history because, in the course of his epic namely The Faerie Queene, he wishes to make occasional references to historical events and historical personages. Clio's function was to record the deeds of heroes; and Spenser wishes his poem to be regarded partly as a historical poem. He invokes Clio as the keeper of the records of the deeds which he is going to describe in his poem. Spenser here regards Clio as the chief of the nine Muses, although actually it was Calliope who was the chief of all the Muses. Thus, Spenser is here making a lax and inaccurate use of classical mythology.

We have also a glimpse into the didactic purpose of Spenser. The two chief themes of his epic poem are (i) the heroic deeds of the knights and (ii) the loves of the knights and the ladies. These were the two chief pursuits of chivalry of the medieval times. But Spenser also adds a third theme to these two. The third theme is allegory. The last line of the first stanza indicates all the three themes of Spenser's poem. "Fierce warres and faithful loves shall moralize my song." A moral allegory runs through the whole of Spenser's poem.

In addition to invoking the help of Clio, Cupid, Venus and Mars, Spenser seeks the patronage of Elizabeth, the reigning Queen of England at the time. Those were the days when royal patronage was very important. Spenser showers glowing epithets on Queen Elizabeth whose radiance he compares to the light of the sun.