Pembrokeshire civil parishes. During the First English Civil War (1642–1646) the county gave strong support to the Roundheads (Parliamentarians), in contrast to the rest of Wales, which was staunchly Royalist. In spite of this an incident in Pembrokeshire triggered the opening shots of the Second English Civil War when local units of the New Model Army mutinied. Oliver Cromwell defeated the uprising at the Siege of Pembroke in July 1648. On 13 August 1649, the Cromwellian conquest of Ireland began when New Model Army forces sailed from Milford Haven. In 1720, Emmanuel Bowen described Pembrokeshire as having five market towns, 45
Pembrokeshire to its proximity to the relatively warm Atlantic Ocean. Inland, average temperatures tend to fall 0.5 °C for each 100 metres increase in height. The air pollution rating of Pembrokeshire is "Good", the lowest rating. The rocks in the county were formed between 600 and 290 million years ago. More recent rock formations were eroded when sea levels rose 80 million years ago, at the end of the Cretaceous Period. Around 60 million years ago, the Pembrokeshire landmass emerged through a combination of uplift and falling sea levels; the youngest rocks, from the Carboniferous Period, contain the Pembrokeshire Coalfield. The