for his condition, obizzo was destined to an obscure future; nevertheless, this situation changed in 1251: his father rinaldo, a hostage of emperor frederick ii since 1238, was poisoned with his barren wife, adelaide da romano. without any other sons to continue his line, the margrave azzo vii saw in obizzo the only chance of survival of the house of este and fought for his recognition as his heir. obizzo was legitimated by the pope innocent iv in 1252, shortly after his mother was drowned in the adriatic.