[1] In 931 he brought Boso to Italy at the same time as he made his son, Lothair, co-ruler in order to strengthen his position against the powerful margrave Lambert of Tuscany.
According to Liutprand of Cremona, the rumours of the time had it that Bertha, unable to conceive, in order to safeguard her second husband's succession, had feigned pregnancy and presented as her own two sons, Lambert and Guy, who were actually the children of others.
[1][b] In his earliest documented presence in Italy, Boso is found intervening on behalf of the Patriarchate of Aquileia on 17 October 931.
[1] The first document recording his rank of "margrave" (marchio) dates to 1 July 932, when he persuaded the king to make a donation to the church of Saint Martin in Lucca.
In order to obtain the march of Tuscany for himself, Boso convinced Hugh to arrest Lambert; who was subsequently blinded in prison.
[1][2] Boso had married his daughter Willa, named for her mother, to Berengar of Ivrea, one of the most powerful margraves in the kingdom.