The Partition of England and Wales into Northumbria, Wales and Wessex.
A History of Cymru following the partition of 1405
The Monks of Chester began a rebellion to install Henry IV's son Henry as the king of England and Wales. This was crushed by King Owain's forces at the Battle of Chirk Following this the University of Chester to cement Welsh values into the former marches.
With the freeing of Wales from England the Cornish saw their chance to be reunited with their Brythonic kin. As tensions within Wessex rose under increased taxes and levies for their wars against Northumbria the Cornish rose in rebellion. Refugees from Cornwall arriving on the south coast of Wales found little food remaining with the harvest leading to food being shared between North and South Wales on the order of Macsen ap Gruffudd Prince of Aberffraw the Lord of Gwynedd and the King's son in an event known as Y Gyfnewid Caredig (The Friendly Exchange) This led to him being known among the people as Macsen Hael or Macsen the Generous.
With the help of Cymru Cornwall managed to gain its independence and joined Cymru.
Considered the beginning of the Wessex Cymru War. Following border skirmishes between Cornwall and Wessex. Wales sent an expedition to the Cornish border