In 589, when the Frankish king Guntram sent an army under the general Boso into Septimania in support of a rebellion by the Arian archbishop Athaloc, Claudius was sent by King Reccared to defeat it.
Most Arian nobles and ecclesiastics followed his example, certainly those around him at Toledo, but there were Arian uprisings, notably in Septimania, his northernmost province, beyond the Pyrenees, where the leader of opposition was the Arian bishop Athaloc, who had the reputation among his Catholic enemies of being virtually a second Arius.