Dydd Owain Glyndŵr: When is it, why is it celebrated and what’s happening in Wales?
Every year on 16 September, Wales remembers one of the most remarkable figures in its history — Owain Glyndŵr.
More than six centuries after he was proclaimed Prince of Wales and launched a rebellion against the rule of Henry IV, Glyndŵr remains an instantly recognisable figure in Welsh history and culture.
But why is Owain Glyndŵr Day celebrated on 16 September? Who exactly was Glyndŵr? And how is Wales marking the occasion in 2026?
This year there is an additional reason for renewed interest in his extraordinary story — with Michael Sheen preparing to portray Owain Glyndŵr on stage in Cardiff, and a brand-new teaser trailer released today to mark Glyndŵr Day.
When is Owain Glyndŵr Day?
Owain Glyndŵr Day — Dydd Owain Glyndŵr — takes place every year on 16 September.
The date takes us back to 16 September 1400, when Glyndŵr was proclaimed Prince of Wales by his supporters at Glyndyfrdwy in the Dee Valley.
It marked the beginning of an uprising against the rule of King Henry IV which was to dominate Welsh affairs for years. The National Library of Wales today commemorates 16 September specifically as a celebration of Glyndŵr’s legacy and leadership.
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Who was Owain Glyndŵr?
Born around 1359, Owain Glyndŵr came from families with connections to the old Welsh princely houses.
For much of his earlier life, however, there was little to suggest that he would become the leader of one of the most significant rebellions in Welsh history.
Among the events preceding the revolt was a bitter land dispute between Glyndŵr and his neighbour Reginald de Grey, Lord of Ruthin. Glyndŵr’s grievances eventually became part of a much wider conflict.
Just two days after his proclamation as Prince of Wales, Glyndŵr and his supporters attacked Ruthin. Other attacks followed at places including Denbigh, Rhuddlan, Flint, Hawarden, Oswestry and Welshpool.
The revolt grew far beyond a local dispute.
By 1404, Glyndŵr had captured Harlech Castle, which became an important stronghold, and he summoned a parliament at Machynlleth. At its height, his campaign presented a serious challenge to English control of Wales.
His ambitions extended beyond the battlefield. Glyndŵr envisaged Welsh institutions of government, church and education, and sought international alliances to support his cause.
Although the rebellion was eventually suppressed, Glyndŵr himself was never captured.
His final years — and even the exact circumstances and date of his death — remain uncertain, adding another layer to a story which has fascinated generations.
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What is happening for Owain Glyndŵr Day 2026?
Events have been taking place across Wales around this year’s anniversary.
Corwen, close to Glyndŵr’s ancestral lands, remains one of the focal points for annual commemorations. This year’s programme has included a church service involving local schoolchildren, a procession and wreath-laying ceremony, together with the R. R. Davies Memorial Lecture.
Harlech Castle is also marking 16 September with an Owain Glyndŵr Parade. The location is particularly appropriate: Harlech became one of Glyndŵr’s most important strongholds after he captured it during the rebellion. Cadw lists today’s parade among its featured events.
At Beaumaris Castle, special history tours have been taking place between 11am and 4pm, exploring both the castle and the story of the Welsh princes.
Celebrations actually began before 16 September. On Sunday, 13 September, children and young people were offered free entry to Cadw-run historic sites around Wales as part of the Glyndŵr Day programme. Many of those castles have direct connections with the uprising.
And Gŵyl Glyndŵr is extending the commemorations beyond a single day, with events taking place between 13 and 19 September at locations around Wales.
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What has Michael Sheen got to do with Owain Glyndŵr Day 2026?
Quite a lot this year.
Welsh actor Michael Sheen will play Owain Glyndŵr in Owain & Henry, a major new play by Olivier Award-winning Welsh playwright Gary Owen.
The Welsh National Theatre and Wales Millennium Centre co-production runs at the Wales Millennium Centre in Cardiff from 5–28 November 2026, with Sheen also co-directing alongside Steffan Donnelly. Linus Roache plays Henry IV.
And the timing could hardly be better for today’s celebrations.
A new teaser trailer featuring Sheen as Glyndŵr was released today, 16 September, specifically to coincide with Owain Glyndŵr Day. It provides the first glimpse of Sheen in action as the Welsh leader ahead of November’s world premiere.
WATCH: Michael Sheen as Owain Glyndŵr in the new Owain & Henry teaser
For anyone encountering Glyndŵr’s story for the first time, the production could introduce one of the defining chapters in medieval Welsh history to an entirely new audience.
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Why is Owain Glyndŵr still important more than 600 years later?
Perhaps because his story has never really disappeared.
There are statues and memorials to him, organisations bearing his name and annual commemorations across Wales. His standard — the four lions of the Glyndŵr banner — has also become one of the recognisable symbols associated with Welsh history.
There is the tantalising ending too.
Unlike so many medieval leaders whose deaths brought their stories neatly to a close, Glyndŵr simply disappeared from the historical record. He was never handed over to his enemies and his burial place remains unknown.
Six hundred and twenty-six years after his proclamation as Prince of Wales, Wales is still talking about him.
And on Owain Glyndŵr Day 2026, perhaps more people than usual will be discovering his story.
Did Ewe Know?
Owain Glyndŵr also found his way into the works of William Shakespeare. He appears as Owen Glendower in Henry IV, Part One — ensuring that the Welsh rebel prince became part not only of Welsh history, but of world literature.
