Oswald was an Ealdorman of Sussex

Kingdom of Sussex

The Kingdom of Sussex or Kingdom of the South Saxons was a Saxon colony and later independent kingdom of the Saxons, on the south coast of England. Its boundaries coincided in general with those of the earlier kingdom of the Regnenses and the later county of Sussex. A large part of its territory...

, jointly with three former kings: Osmund

Osmund of Sussex

Osmund was a King of Sussex, apparently reigning jointly with Oswald, Ælfwald, and Oslac.According to the Anglo-Saxon Chronicle, version D, Osmund was reigning in Sussex when Archbishop Cuðberht died in 760, so his rule commenced before that event.He issued a charter, dated 762 in error for 765,...

, Ælfwald

Aelfwald of Sussex

Ælfwald was a King of Sussex, who reigned jointly with Ealdwulf and Oslac, and probably also with Oswald and Osmund.Ælfwald witnessed an undated charter of Ealdwulf, believed to be from about 765, with his name corruptly recorded as Ælhuuald rex....

, and Oslac

Oslac of Sussex

Oslac was a King of Sussex. He reigned jointly with Ealdwulf and Ælfwald, and probably also Oswald and Osmund.Oslac witnessed an undated charter of Ealdwulf, believed to be from about 765, with his name corruptly recorded in the surviving revision as Osiai rex .After the conquest of Sussex by Offa,...

.

He witnessed a charter of Offa

Offa of Mercia

Offa was the King of Mercia from 757 until his death in July 796. The son of Thingfrith and a descendant of Eowa, Offa came to the throne after a period of civil war following the assassination of Æthelbald after defeating the other claimant Beornred. In the early years of Offa's reign it is likely...

, King of Mercia, dated 772

772

Year 772 was a leap year starting on Wednesday of the Julian calendar. The denomination 772 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.- Europe :* Frankish king Charlemagne starts fighting...

as Osuualdus dux Suðsax http://www.anglo-saxons.net/hwaet/?do=seek&query=S+108. He was listed ahead of the three former kings Osmund, Ælfwald, and Oslac, which implies that his rank was higher. It is probable that all four were former Kings of Sussex, demoted after Offa's conquest. However, this is mere speculation; there is no actual evidence that Oswald ever reigned as king.

Oswald is not known to have issued charters of his own.