G. A. Henty 
In the Irish Brigade A Tale of War in Flanders and Spain [EPUB ebook] 

Excerpt: "The evils arising from religious persecution, sectarian hatred, ill government, and oppression were never more strongly illustrated than by the fact that, for a century, Ireland, which has since that time furnished us with a large proportion of our best soldiers, should have been among our bitterest and most formidable foes, and her sons fought in the ranks of our greatest continental enemy. It was not because they were adherents of the house of Stuart that Irishmen left their native country to take service abroad, but because life in Ireland was rendered well-nigh intolerable for Catholics, on account of the nature and severity of the laws against them, and the bitterness with which those laws were carried into effect."