Anselm was expelled from Lucca around 1080, with the help of Emperor Henry and Guibert, Antipope Clement III, after the defeat of the papal defender, the Countess Matilda of Tuscany at the Battle of Volta Mantovana (October 1080).

[4] Anselm fled first to the shelter of Moriana, an episcopal stronghold only a few miles up the Arno from Lucca and was accompanied by Bardo, a priest who later wrote his vita, and then retired to Canossa as spiritual guide to Countess Matilda.

Bishop Benzo of Alba, Henry IV's fiercely partisan supporter, tells how Matilda and Anselm stripped the monasteries to send gold and silver to Gregory in Rome.

Sometime later, Gregory VII made him papal legate in Lombardy,[4] with authorization to rule over all the dioceses which had been left without bishops due to the conflict between pope and emperor.

Anselm was well versed in scripture and wrote some important works attacking lay investiture and defending Pope Gregory against Antipope Clement III and Emperor Henry IV.