Although England and Wales gradually polarised into two camps during1642, the First Civil War did not commence officially until August 22nd 1642 when Charles raised his standard at Nottingham and called on all loyal men to support him. This unambiguous demand for loyalty made it increasingly difficult to remain neutral, and England was on course for its first internecine conflict since the Wars of the Roses.
Map 1 depicts the territorial balance of power in autumn 1642. Parliament controlled the more economically advanced south and east, while Royalism was strongest in the north and west. Some historians interpret the Civil Wars as an expression of the determination of the bourgeoisie (manufacturers, traders, entrepreneurs) to seize the political power which they were excluded from by the traditions of ecclesiastical and monarchical power, and while not all historians endorse this theory, Parliament's greater strength in the more economically advanced areas certainly gives credence to this intepretation. Parliament controlled most of the major cities and ports and the navy was largely in its hands.
The first six months of the war proved inconclusive, but in 1643 the Royalists made significant advances.
Map 2 reveals how Royalist military successes during 1643 translated into increased territorial influence.
Two engagements in the south-west (Lansdown and Roundway Down) in July 1643 were significant in expanding Royalist territory in the south west and on 20th July, Prince Rupert captured the strategically important port of Bristol. The Royalist forces made further advances in the north-west (capturing Bolton, Wigan, Liverpool) throughout the first half of 1644, and June 1644 represents the zenith of Royalist military success, prior to Marston Moor.
Map 3 clearly reveals the importance of Marston Moor in tilting the balance of power in Parliament's favour. With 4000 men killed and perhaps 1500 taken prisoner, Marston Moor was a major military disaster for the Royalists and the bloodiest battle of the Civil Wars.
Following Marston Moor, Parliament extended its influence throughout the entire North of England and regained territory formerly captured by Rupert. The Parliamentary faction also underwent a process of military and political re-organisation during the second half of 1644. Royalist influence in Parliamentary territory during this phase of the war was confined to a few strongholds such as Bolton Castle, Carlisle and Lichfield. Royalist fortunes deteriorated further throughout 1645.
Map 4 clearly reveals the importance of Naseby in determining the outcome of the First Civil War. Against Prince Rupert's advice, Charles decided to engage a much larger Parliamentary force in battle, and with 1000 dead and 4000- 6000 taken prisoner, Naseby was a major disaster for the Royalists, effectively finishing them as a military force. In the months which followed, Parliament won successive battles at Langport and Rowton Heath and re-captured Bristol in September 1645. With the defeat of Montrose at Philiphaugh (September 1645) and the failure of Charles' Irish strategy in early 1646, the game was up for the Royalist cause by spring 1646. On 5th May 1646, Charles surrendered to the Scottish Covenanters, bringing the First Civil War to an end.