Verdi had read the ultra-Romantic play in April 1844, probably introduced to it by his friend Andrea Maffei who had written a synopsis.
A letter to Francesco Maria Piave (with whom he had worked on both Ernani and I due Foscari) had included the subject of Attila as opera number 10 on a list of nine other possible projects, and in that same letter, he encouraged Piave to read the play, which musicologist Julian Budden describes as having "sprung from the wilder shores of German literary romanticism [and which contains] all the Wagnerian apparatus - the Norns, Valhalla, the sword of Wodan  [sic], the gods of light and the gods of darkness."
 He continues: "It is an extraordinary Teutonic farrago to have appealed to Verdi".

Verdi works with Solera
But, as Attila was to be the second opera Verdi would be writing for Venice, he appears to have changed his mind about working with Piave as the librettist and then convinced him to relinquish the project, seemingly preferring to work with Solera, who had been his librettist for both Nabucco and I Lombardi, two operas which employed the format of large choral tableaux and something which the librettist was prepared to re-use for the new opera.
No clear reason for this change seems to have emerged, except that Gabriele Baldini speculates that, in returning to Solera, he was more comfortable working with a librettist who was more suited to "sketching epic sagas and historical-religious frescoes.

Solera's approach to the project was to emphasize an appeal to Italian, specifically Venetian, patriotism, while ignoring many of the elements of the play.
 These included reversing the order of key scenes and, in the case of the opening scene showing the foundation of Venice, totally inventing it.
But the pace began to slow as, firstly, illness limited the composer's ability to do much work.
 Then came the second blow: Solera left the project altogether and followed his opera singer wife to Madrid where he became director of the Royal Theatre, leaving only the draft sketch of the third act.

Verdi returns to Piave
As things turned out, Verdi returned to Piave for the completion of act 3 - with Solera's blessing.
 However, the relationship between composer and the new librettist worsened in a variety of ways, especially over the use of stage bands in the context of the composer claiming to think in terms of his work being a grand opera:  "Aren't Guillaume Tell and Robert le Diable grand operas?
 Yet they don't contain a band."

And the differences between Piave's version and what Solera (who received a copy of Piave's act 3) had originally conceived were so great as to cause a final rift between Verdi and his long-time collaborator;  the composer's ideas of musical theatre had moved far ahead of his older colleague.
Verdi had read the ultra-Romantic play in April 1844, probably introduced to it by his friend Andrea Maffei who had written a synopsis. A letter to Francesco Maria Piave (with whom he had worked on both Ernani and I due Foscari) had included the subject of Attila as opera number 10 on a list of nine other possible projects, and in that same letter, he encouraged Piave to read the play, which musicologist Julian Budden describes as having "sprung from the wilder shores of German literary romanticism [and which contains] all the Wagnerian apparatus - the Norns, Valhalla, the sword of Wodan  [sic], the gods of light and the gods of darkness."  He continues: "It is an extraordinary Teutonic farrago to have appealed to Verdi".
Verdi works with Solera
But, as Attila was to be the second opera Verdi would be writing for Venice, he appears to have changed his mind about working with Piave as the librettist and then convinced him to relinquish the project, seemingly preferring to work with Solera, who had been his librettist for both Nabucco and I Lombardi, two operas which employed the format of large choral tableaux and something which the librettist was prepared to re-use for the new opera. No clear reason for this change seems to have emerged, except that Gabriele Baldini speculates that, in returning to Solera, he was more comfortable working with a librettist who was more suited to "sketching epic sagas and historical-religious frescoes.
Solera's approach to the project was to emphasize an appeal to Italian, specifically Venetian, patriotism, while ignoring many of the elements of the play.  These included reversing the order of key scenes and, in the case of the opening scene showing the foundation of Venice, totally inventing it. But the pace began to slow as, firstly, illness limited the composer's ability to do much work.  Then came the second blow: Solera left the project altogether and followed his opera singer wife to Madrid where he became director of the Royal Theatre, leaving only the draft sketch of the third act.
Verdi returns to Piave
As things turned out, Verdi returned to Piave for the completion of act 3 - with Solera's blessing.  However, the relationship between composer and the new librettist worsened in a variety of ways, especially over the use of stage bands in the context of the composer claiming to think in terms of his work being a grand opera:  "Aren't Guillaume Tell and Robert le Diable grand operas?  Yet they don't contain a band."
And the differences between Piave's version and what Solera (who received a copy of Piave's act 3) had originally conceived were so great as to cause a final rift between Verdi and his long-time collaborator;  the composer's ideas of musical theatre had moved far ahead of his older colleague.
Attila (opera)