Guaifer was the prince of Benevento from 878, the death of his uncle Adelchis

Adelchis of Benevento

Adelchis was the son of Radelchis I, Prince of Benevento, and successor of his brother Radelgar in 854.It was given to Adelchis to preserve the ancient principality and its independence in the face of repeated assaults by the Saracens from the south, the Emperor Louis II from the north, and...

, to his own death a short three years later, in 881. Guaifer was the son of Radelgar

Radelgar of Benevento

Radelgar was the eldest son of Radelchis I of Benevento and he succeeded him as Prince of Benevento on his death in 851. Radelgar's mother was Caretrude and his brother was Adelchis....

, but he was too young to succeed on his father's death in 854 and so had to await the death of his uncle first.

In 879, during the contest over the throne of Capua and its diocese

Diocese

A diocese is the district or see under the supervision of a bishop. It is divided into parishes.An archdiocese is more significant than a diocese. An archdiocese is presided over by an archbishop whose see may have or had importance due to size or historical significance...

, he came to the aid of Pandenulf

Pandenulf of Capua

Pandenulf was the Count of Capua, claiming that title from 862 and holding it successfully during the tumultuous civil war of 879 – 882. He was the son and successor of Pando, but was removed on his father's death by his uncle the bishop, Landulf II....

 against his own brother-in-law, Lando III

Lando III of Capua

Lando III was the count of Capua for two years and ten months from 882 to his death. He was a son of Landenulf, gastald of Teano, and grandson of Landulf I of Capua....

.