But a marked distinction grew up between a small portion of Ireland and the rest. James I.'s plantation of Ulster had been far more drastic and thorough than any operation of the kind before or since. Later immigrants had flowed in, and at the beginning of the eighteenth century in the north-eastern portion--the predominantly Protestant Ulster of to-day--Scotch Protestant tenants, mainly Presbyterian, were thickly settled, and formed an industrious community of strong and tenacious temper. In the original leases granted by the concessionaires in the seventeenth century, fixity of tenure was implied, and a nominal rent levied, somewhat after the American model; but under the example of other Provinces, and the economic pressure exerted by the growth in the Catholic population, these privileges seem to have been almost wholly obliterated. The absentee landlords, reckless of social welfare, exacted the rack or competitive rent. As in the south and west, tithes to the Established Church and oppressive and corrupt local taxation for roads and other purposes, aggravated the discontent. For agrarian reasons only--and there were others which I shall mention--many thousands of Protestants left Ireland for ever. It required a long period of outrage and conspiracy, attaining in 1770 the proportions of a small civil war, and at the end of the century, by the anti-Catholic passions it inspired, wrecking new hopes of racial unity, to establish what came to be known as the Ulster Custom of Tenant Right. If Protestant freemen had to resort to these demoralizing methods to obtain, and then only after irreparable damage to Ireland, the first condition of social stability, a tolerable land system, the effect of the agrarian system on Catholic Ireland, prostrate under the Penal Code, may be easily imagined.