boundary is formed by the river Mersey, which is a considerable stream for much of the border; and the low-lying land to the north of the river was in the 17th century mostly undrained marsh, forming a strong barrier. Thus Lancashire was effectually isolated by its natural boundaries from the neighbouring counties. These geographical conditions had two great effects on the war in Lancashire. In the first place they enabled the issue to be decided within the county without help or hindrance from outside. There was of course some connection with Yorkshire and Cheshire, but mostly in the later years of the war; at first the war was fought out by local troops within the county itself. This is no drawback to the study of our subject, for the Civil War was very largely a local war and can best be studied locally. It was not, like the Wars of the Roses, a dynastic struggle, in which the nation generally had no direct interest; but its causes, political, religious and social, went down to the primary divisions of opinion among Englishmen which have existed ever since, and to some extent do so to-day. The course of the Civil War in Lancashire shows the working out on a smaller stage of the main principles of the period. The religious question was of course very prominent. The local royalists were either in sympathy with the King's ecclesiastical policy, or they were Roman Catholics. Lancashire had been conservative in religion, and there was a very large Roman Catholic population; particularly the west coast and the Fylde adhered, as to some extent they still do, to the ancient faith. And though at first Catholics were not openly included in the royalist armies, and indeed Lord Strange's first warrants definitely excluded them,[1] the exclusion was only temporary. A petition of the Lancashire recusants to the King to bear arms 'for their own defence' was granted, and paved the way for their admission to the royalist ranks. Some of the most prominent of the Lancashire royalist leaders were Roman Catholics. The Puritan element was strongest in the east and south-east of the county, especially in Manchester and in Bolton, 'the Geneva of the North'; and it was these places which formed the stronghold of the Parliament's cause in Lancashire. The Hundreds of Salford and Blackburn were the only two out of the six Hundreds of the county which were on the popular side in 1642. But a distinctive development took place in the later years of our period. The Lancashire Parliament men were Presbyterians; indeed so strong was Presbyterianism as to produce in this county the most completely organized system in England of Presbyterian church government. This development occurred after the end of the first Civil War. The Parliament therefore had the steady support of the Lancashire leaders in the early part of the struggle; but with the growth of Independency, they became more and more out of sympathy with the ruling powers.