Pembrokeshire: History
Human habitation in what is now Pembrokeshire dates back to between 125,000 and 70,000 years ago, with prominent prehistoric sites including Pentre Ifan and other Neolithic remains. Aerial surveys during the 2018 heatwave revealed many previously unrecorded sites, and in the same year, Wales's first known Celtic chariot burial was discovered in Llanstadwell. Roman influence was limited; although a few forts, coins, and roads have been found, much of the area remained beyond sustained Roman control. In the sub-Roman period, the Irish Déisi settled and merged with local populations, forming the Kingdom of Dyfed, which became part of Deheubarth in the 10th century. The region saw Viking raids and limited settlement.
Normans and Flemings arrived between 1067 and 1111, building castles such as Pembroke Castle and transforming Dyfed into the county of Pembroke. Although Norman control was contested by Welsh rulers including The Lord Rhys and Llywelyn the Great, it endured in many parts of the region. Pembrokeshire was declared a county palatine in 1138 and saw a wave of Flemish settlement. In 1485, Henry Tudor had launched his campaign from Pembroke, ultimately becoming Henry VII of England. The Laws in Wales Acts 1535 and 1542 later reorganised it into seven hundreds, aligning it with the English shire system. The county supported Parliament in the English Civil Wars, with Oliver Cromwell besieging Pembroke in 1648 following a local mutiny.
In the 18th and 19th centuries, Pembrokeshire remained largely agricultural, with modest urban centres and limited industrial growth. The Battle of Fishguard in 1797 marked the last invasion of Britain, ending in French surrender. Poor relief and infrastructure remained key concerns, with water supply improved only later in the century. In the 20th century, military use of the county intensified, particularly during the world wars: a naval base at Milford Haven, multiple airfields, D-Day training by U.S. forces, and accommodation of German POWs all featured. Pembrokeshire's wartime casualties are commemorated at the County of Pembroke War Memorial. After 1945, modern development included the construction of the Llys y Fran reservoir (1972), with the local economy later benefiting from tourism, agriculture, and energy infrastructure.
In February 1996, the Pembrokeshire coast suffered the UK's (then) third worst oil spill when the Sea Empress ran aground at the entrance to Milford Haven.