The genesis of Wessex is twofold: on the one hand a number of small but powerful kingdoms based in the Upper Thames Valley, the Gewissæ, and on the other the power-base of the Solent and the important economic site of Hamwic, later Southampton. Early succession disputes diluted the power of the kingdom, but by the 8th century the Westseaxe 'West Saxons', had become the dominant power in the south-west and extended their rule into neighbouring territories such as Devon (Dumnonia) and eastwards into Sussex, Berkshire and Kent. With the piecemeal destruction of the kingdoms of eastern and middle Britain, Wessex came to represent the last English polity to resist the Danish advance. Through a combination of strategic planning, military preparation, stronghold construction and educational reform, the West Saxons under Alfred (Ælfræd) not only withstood the Viking onslaught but brought the Danes to a territorial division agreement at the Treaty of Wedmore, and began the process of re-conquest. Alfred is the only English king to be styled "the Great". The West Saxon royal line provided all the kings of the united kingdom of England until the childless Edward the Confessor died in 1066, provoking the assumption of power by Harold Godwineson.

Ecgberht is one of the more remarkable kings of the West Saxons, although his achievements have been overshadowed by those of his descendants, Alfred and Athelstan. He was king of the West Saxons from 802 to 839 AD, a respectable reign for an Anglo-Saxon monarch. From around 825 AD Ecgberht began extending Wessex's influence to the east into Sussex, Kent and Essex, and ultimately he became over-king in East Anglia. In the last year of his life he gained control of the traditional enemy, Mercia. Indeed, after Ecgberht's defeat of the Mercian forces at Ellendun in 825, Mercian power never fully recovered and it was this coup which induced all the southern Anglo-Saxon kingdoms to submit to him. Ecgberht's principal residence was at Winchester, and it was this city which formed the political centre of England for the next 150 years.

Son of Ecgberht and a sub-king of Kent, Æthelwulf's reign was beset with premonitions of the Viking tide to come. In later writings we find him to have been a conscientious man who took his royal duties seriosly and who was interested in the affairs of the church. He made two pilgrimages to Rome with his young son, Alfred. The breadth of experience which Alfred gained on these expeditions offered the young prince fresh ideas about defence, about gaining and holding territory, about naval warfare, about economic activity and about the tactical and strategic possibilities of terrain. Æthelwulf was King of Essex, Kent, Surrey and Sussex in the period 825-839; he was effective king of all southern England, 839-855; due to Viking activity, he was King of Essex, Kent and Sussex only from 855-858.

Son of King Aethelwulf of Wessex, Aethelberht was a subregulus of Kent, Essex and Sussex from A.D. 858-860, and effectively king of all southern England from A.D. 860-865/6. During his reign, Viking activity intensified and the king had to defend his own seat at Winchester against seaborne raiders. Æthelberht's rule was characterized by careful planning against further Viking ativity - planning on which his younger brother, King Alfred, was later able to capitalize.

King Æthelred I was a son of King Æthelwulf of Wessex, one of five brothers. Æthelred succeeded Æthelberht to the southern territory comprising Wessex and the south-eastern region of Essex-Kent-Surrey-Sussex. On 4th January, 871 at the Battle of Reading, Æthelred suffered a crushing defeat, although he turned this into victory soon after at Ashdown. His subsequent engagements with the Vikings were inconclusive, and he was killed at the battle of Merton on 23rd April, 871 A.D. Æthelred was buried at Wimborne in Dorset and was popularly regarded as a saint, but never canonised. He was succeeded by his younger brother, King Alfred the Great.

Alfred (Ælfræd) was the youngest son of King Æthelwulf, and the brother and successor to Æthelred I. As the youngest son, he was marked out for a career in the church and was encouraged to indulge his intellectual curiosity. The prince accompanied his father to Rome as a child and was given a symbolic office by the Pope. The exposure he gained to the wider world of Western Europe was later invaluable: he adopted Carolingian ideas such as defended bridges to protect rivers, which he realized with the construction of the 'burh' or fort at Southwark opposite London. His graetest achievements were not merely military though - he reformed the economic base of Anglo-Saxon towns, constructed forts, built warships, re-organized the military and instituted a nationwide programme of learning which eased the administrative burden of government. Early in his reign, Alfred was driven into hiding by a Viking raid over midwinter, and took refuge in the marshes in Somerset on the island of Athelney. Rather than give up and head for exile in Rome, Alfred raised his forces in secret and met the Danes in battle at Edington where he won a convincing victory. A peace treaty followed, whereby the Viking leader, Guthorm, received Christian baptism and withdrew his forces from Wessex, while Alfred recognized Danish control over East Anglia and parts of Mercia, an area known as the "Danelaw". After his death, Alfred was buried in his capital city of Winchester, and is the only English monarch in history to bear the title "the Great."

Edward was the eldest son of Alfred the Great and Ealhswith; he succeeded his father in 899 and continued Alfred's policy of keeping the Vikings off-balance by harrying their borders and outmanoeuvring their armies. After an initial peace treaty, Edward used the time he gained to fortify strongholds and re-equip his armies. By 909 AD the king took a more aggressive stance and began a campaign of harrassment and raiding. The following year, a joint Mercian and West Saxon army marched north and defeated the Viking army completely at Tettenhall (Staffordshire). Edward then concentrated his attentions on the Danes of East Anglia and the Five Boroughs of the East Midlands. After his sister, Æthelflæd's death in AD 918, Edward was able to take advantage of his niece, Ælfwinn's minority and brought Mercia under direct Wessex control. Two years later, the kings of the north - including Sigtrygg Caech of York, Constantine II of the Scots and Donald mac Aed of Strathclyde - met Edward at Bakewell (Derbyshire) and recognised his overlordship. In 924, he led an army north once more to put down a rebellion in Cheshire. He died at Farndon-upon-Dee in that county on 17th July. Edward is known as 'the Elder' due to the post-Norman-invasion documentary convention that early English kings' reign did not form part of the royal title sequence: the eight official (post-Norman) kings called Edward are supplemented by three more - 'the Elder', 'the Martyr' and 'the Confessor'.