Seventh Century Britain - Kingdoms in Turmoil

During the early 600s, Britain was a mass of messy territorial conflicts resulting from large kingdoms. These large kingdoms, such as Sussex, Wessex, Essex, East Anglia, Mercia, and Kent were the result of the invading Germanic tribes of the Anglo-Saxons and the Jutes. These migrants pushed the indigenous Britons north and settled around the fertile southern farmlands of Britain, even managing to continue north. These kingdoms were in a constant state of fluctuation and were not the only kingdoms but rather only the larger kingdoms of Britain. Smaller tribes of people formed kingdoms outside the borders of and sometimes within these larger Anglo-Saxon kingdoms, sometimes becoming absorbed within them in this constant flux of kingdoms. Many of the kings of these large realms had sub-kings, smaller rulers that had descended from independent kingdoms that had been absorbed.

The constantly shifting power between kingdoms led one kingdom or another every few years to gain a significant amount of power over the other kingdoms, and therefore over all of Britain. This political domination of the British Isles was generally very short-lived though broad in terms of the power they had over other kingdoms. The first of these "over-kings", as historian John Blair puts it, was Aelle, the king who ruled in Anglo-Saxon Sussex. It wasn't until in 616 when Northumbria produced two kings in succession named Edwin, who ruled from 616 until 632 and Oswald, reigning from 633 to 642. These two became over-kings (the fifth and sixth respectively according to contemporary history the Venerable Bede) after the king of East Anglia, Raedwald, brought an army into Northumbrian territory.

Oswald's army had killed the king of Gwynedd (south of the modern-day Isle of Man) during his westward expansion for the duration of his kingship in Northumbria. The king who was slain, a Christian king named Cadwallon, had an ally who avenged his death. This pagan king, named Penda, and his army killed Oswald of Northumbria but was defeated and killed by Oswald's successor Oswy, the seventh over-king of Britain during the seventh century BC. This constant flux of power in all of the kingdoms of Britain is attributed to the wealth of the kings. The kings who were able to bring together the most wealth were generally able to attract the most warriors and assemble the most dependable military forces. The fluid succession of kingships was due to the English society itself. Being a "warrior society" the military aristocracy provided a strong base for the cultural literature of the era that seemed based off of heroic deeds, such as the larger-than-life hero Beowulf, who fought with monsters and demons that reflect pre-Christian mentality in ancient Britain.

Sources:

College lecture

The Oxford History of Britain, edited by Kenneth O. Morgan