Career
In 1376, with the support of the Ghibelline party, he took advantage of a revolt of Forlì against the Papal authority, to rebuild the seigniory established by his ancestor Francesco I in 1315. Pope Urban VI named him Papal vicar of Forlimpopoli and Castrocaro Terme from 1379. In 1382, with the help of Alberico da Barbiano, he pushed back the assault of Louis of Anjou.
Sinibaldo died in 1386, probably poisoned.