The very title "Prince of Wales" is loaded with historical tensions. It has traditionally been bestowed upon the eldest son of the reigning British monarch, and its use dates back to 1284. It is in that period of the Middle Ages that those tensions have their roots.

There were princes in Wales long before 1284 - the native Welsh aristocracy who proudly traced their ancestry to the earliest Celtic peoples who populated most of the British Isles centuries before the first Saxon invaders came to the eastern shores.

Since the Dark Ages, those Celtic peoples had gradually been pushed back northwards and westwards by successive waves of invaders from Northern Europe, but within the mountainous territory of Wales they found a natural stronghold within which they were able to preserve and develop their own distinctive culture, laws and kinship patterns.

The Normans arrived in Britain in 1066 and, with their ruthless and highly-developed military techniques, quickly overran the Saxon territory now known as England. But they found Wales a harder nut to crack. There, the native dynasties, aided by the inhospitable terrain, held out for another two centuries.

The people of Wales have come to accept their prince

Successive campaigns by Norman kings to subjugate England's western neighbour met with varying degrees of success. The Normans, helped by the perpetual feuds and divisions within the Welsh dynasties, were able to conquer and settle areas of lowland Wales, but the extensive highlands remained centres of resistance, and astute Welsh rulers like Llywelyn the Great and Llywelyn ap Gruffudd were able to ensure the allegiance of other Welsh rulers - and eventually of the Normans themselves - to their claim to be princes of Wales.

That uneasy balance of power came to an end in 1282, when Edward the First of England launched an all-out offensive to drag Wales into his control, and gained an unexpected swift victory when the Welsh Prince, Llywelyn ap Gruffudd was killed at Cilmeri near Builth Wells in Powys in an encounter some historians attribute to chance, others to treachery.

Edward lost no time in consolidating his gain. He built a series of castles to form a stranglehold around the Welsh heartland of Snowdonia. These castles, including Caernarfon, Beaumaris, Conwy and Harlech were state-of-the-art military architecture of their time and were hugely expensive, but were thought a price worth paying for securing a unitary state. Today they provide some of Wales's most stunning tourist attractions - or some of the most oppressive symbols of its political subjection, depending on the point of view.

Edward recognised the importance of symbolism to a people like the Welsh, for whom poetry and images were traditionally potent forces. It was this which led him to proclaim his own infant son Prince of Wales at Caernarfon two years after his conquest of Wales, thereby appropriating the title previously only borne by the native princes.

However, Welsh political resistance was not yet a spent force. At the start of the 15th century, the Welsh nobleman Owain Glyndwr led a national revolt against English rule which succeeded in taking most of Wales out of English control. In 1400, Glyndwr, who claimed descent from the native Welsh princes, he proclaimed himself Prince of Wales and established a parliament at Machynlleth.

That short-lived period of self-government came to an end in 1408 when an English war of attrition finally stripped Glyndwr of the land he had regained.

Later that century, the Tudors, a dynasty with genuine descent from the Welsh princes, came to the throne of England. To romantically-minded optimists, this meant the Welsh had regained control of the Island of Britain. The hard-headed Tudors, however, while ready to invoke Welsh sentiment for political gain, had no intention of allowing Wales to be a separate entity within the kingdom they were creating, and their unilateral Act of Union of 1536 extinguished Welsh laws and ruled the Welsh language out of public life.

David Lloyd George gave the title Prince of Wales greater political significance

The title Prince of Wales had little political significance in the following centuries, and next came to prominence in Wales when David Lloyd George engineered the investiture of the future Edward the Eighth at Caernarfon castle in a ceremony which flattered the sensibilities of the Welsh as co-partners with England in the British imperial ideal.

The second investiture of the 20th century, however, was to be a much more fraught affair. It was against a background of growing political discontent in Wales that the 21-year-old Prince Charles was formally invested with the title Prince of Wales at Caernarfon in 1969.

The 1960s saw a groundswell of Welsh nationalist activity, including a campaign of civil disobedience in an attempt to secure public status for the Welsh language, and a bitter campaign against the decision to drown the village of Capel Celyn to create a reservoir. Plaid Cymru had gained their first-ever MP, when Gwynfor Evans was elected for Carmarthen in 1966.

The investiture of Prince Charles was fiercely opposed by Welsh nationalists, including the paramilitary Free Wales Army, who saw the investiture of an "English" prince of Wales as an insult and a cynical attempt to harness Welsh national feelings to the interests of the British status quo.

Although widely supported by the Welsh establishment, and by the vast majority of the Welsh public, the investiture was conducted against a background of protests and bombings carried out by a minority of nationalists. These culminated in the deaths of two members of the Mudiad Amddiffyn Cymru group who were killed by their own bomb on the eve of the royal event.

Public criticism of the prince was blunted by his youth, his personal charm and by his conscientious attempts to learn the Welsh language at Aberystwyth. The investiture event passed off largely peacefully, and seemed to have fulfilled what cynics had claimed was its aim, namely to stifle burgeoning nationalism in essentially British pomp and ceremony.

The young prince worked hard to learn Welsh, but spent more time in Scotland

Since his investiture, Charles's relations with Wales have shown strain on occasion. There has been criticism that he spends too little time in Wales, and that he seems far fonder of Scotland than of the country which gave him his title. This was countered by what was called a "charm offensive" in the 1990's, in which the Prince rebranded some of his activities in Wales, most notably by conducting special honours ceremonies in his own principality rather than asking Welsh recipients to travel to London. On one occasion, while making a plea for the preservation of the Welsh language and rural way of life, he quoted with approval some of the most powerful writings of the father of modern Welsh nationalism, Saunders Lewis.