A line drawn from Whitehouse on Belfast Lough due west to the Clady River, thence by the river itself to Muckamore and Lough Neagh, marks the boundary between the Diocese of Down and the Diocese of Connor. North of this line to the sea and the Bann, including the greater part of the County Antrim and a small portion of Derry, is the Diocese of Connor. South of the line, the remainder of Antrim, except the parish of Aghalee, belonging to Dromore, belongs to the Diocese of Down, as also the whole of the County Down, except the baronies of Iveagh and part of Kinelearty. The extent of the united dioceses is 597,450 Irish acres (about 576 sq. Miles).

Each diocese was a collection of ancient sees. Within the limits of Down, and founded in St. Patrick's time, there were: Raholp, founded by St. Tassach, Gortgrib by Vinoch, Bright by Loarn, Mahee Island by St. Mochay, Moghera by St. Donard. There were also: Moville, founded by St. Finnian, and Bangor by St. Comgall, the later an abbey, but often ruled in aftertimes by a bishop. St. Fergus is named as first Bishop of Down. In ancient times the place was called Dun Celtair, Celtair being one of the Red Branch knights. Afterwards it was called Dun-da-Leth-Glaisse, "the fort of the two half-chains". According to tradition, two young chiefs had long pined in King Laeghaire's prison. St. Patrick miraculously struck off the chain which bound them, and the prisoners, thus released, hastened to their father's residence at Dun Celtair, flinging from them the pieces of the severed chain; hence the new name. A further change occurred after St. Patrick's death. Dying at Saul (493), he was buried at Down, which then contained no church. Subsequently the remains of St. Brigid were brought there from Kildare, as were some relics of St. Columba from Iona. Meanwhile the ancient Dun Celtair had become Downpatrick, a town overshadowing all the neighboring towns, the capital also of the Diocese of Down, which in process of time absorbed all the surrounding sees.

Like Down, Connor, founded in 480 by St. Macnisse, was a collection of smaller sees. These were Kilroot, Drumtullagh, Culfeightrim, Coleraine, Inispollen, Armoy, and Rashee. The date of the founding of each of these sees is uncertain, as also the dates of their absorption; nor can a regular succession of bishops be discovered. By the twelfth century all the sees had ceased to exist except Connor. Its western boundary then was the Roe; but by the synod of Rath-Breasail (1118), when the number and limits of the Irish dioceses were fixed, the Bann was made the western boundary of Connor, and Down was joined to it, but only for a brief period. In 1124 St. Malachy became Archbishop of Armagh; but when he resigned the primacy, in 1137, he became Bishop of Down, again dividing the two sees. This separation was recognized by the Synod of Kells (1152), and continued till 1441, when John Cely, Bishop of Down, was deprived for having violated his vow of chastity. Meanwhile the annals record the death of many distinguished men, bishops and others, connected with both dioceses. It is further recorded that in 831 Connor was plundered by the Danes, and Down in 942; that in 1177 Downpatrick was captured by John de Courcy, who imprisoned the bishop; that in 1183 de Courcy turned the secular canons out of the cathedral and replaced them by Benedictine monks from Chester; that in 1186 the relics of St. Patrick, St. Brigid, and St. Combra were discovered there and reinterred in the church with great solemnity; that in 1315 a great battle was fought at Connor; and that the whole extent of the two dioceses suffered grievously during the invasion of Edward Bruce.

The primate John Prene resisted the union of Down with Connor in 1441, and it did not finally take effect till 1451. Since that date both dioceses, recognized as one, have remained under the rule of one bishop. During the troubled times of the Reformation and the wars of the O'Neills, the Ulster counties suffered much, though the old Faith was still maintained. But the plantation of Ulster replaced the greater number of the Catholics by English Protestants and Scotch Presbyterians. Later on, in the contests of the seventeenth century, the tide of war frequently rolled over Antrim and Down, with consequent destruction of Catholic property. The penal laws followed; and such was the combined effect of plantation and proscription that in 1670 in the whole of Down and Connor there were but 2500 Catholic families. For nearly sixty years subsequently the diocese was ruled by vicars. When at length the pressure of penal legislation was removed Catholicism revived rapidly. In the period from 1810 to 1840 no less than forty new Catholic churches were built. The progress thus made under Dr. Crolly (1825-1835) and Dr. Denvir (1835-65) was continued under Dr. Dorrian (1865-86) and Dr. MacAlister (1886-95); nor did any of his predecessors show greater energy and zeal than Dr. Henry, whose death occurred with such tragic suddenness early in 1908. During the nineteenth century splendid churches were built at Newtownards, Hollywood, Balymoney, and Belfast, and on every side visible signs of Catholic progress appeared.

This prosperity is largely due to the rapid growth of Belfast. Situated on the shores of Belfast Lough, its site was occupied in the sixteenth century only by a strong castle, then in the hands of the O'Neills of Clannaboy. From them it passed at the close of the century to the British Government, and in 1603 the castle and land adjoining were granted by King James to Sir Arthur Chichester. He laid out and planted a small town, which, in 1613, was made a corporation by royal charter. Its growth was slow, and during the seventeenth century it was entirely overshadowed by the neighboring town of Carrickfergus. About 1700, Belfast had a population of 2000, and a good deal of trade; in 1757 a population of 8000. Henceforth its rise was rapid and continuous. Its population in 1871 was 174,000; in 1881, 208,122; in 1891, 255,950; in 1901, with an enlarged city area, 348,876. It sends four members to Parliament, and is ruled by a lord mayor, fifteen aldermen, and forty-five councilors. In commerce and shipping, in trade and manufactures, it is the first city in Ireland. Catholicism has more than kept pace with the general advance of the city. In 1708 there were but seven Catholics in Belfast, and not till 1783 was there a Catholic church. Belfast is now the episcopal seat, with ten city parishes, a flourishing diocesan seminary, and many educational and charitable institutions. Among the remarkable men of the diocese the following may be mentioned: St. Macnisse, the patron saint of Connor, and St. Malachy, the patron saint of Down; St. Tassach, who attended St. Patrick in his last illness; St. Comgall, who founded the monastery of Bangor; St. Finnian, founder of Moville; St. Colman Ela, founder of Muckamore in Antrim; St. Mochay, Bishop on Nendrum; St. Donard, Bishop of Maghera; St. Dochona, Bishop of Connor. In the sixteenth century the notorious Miler Magrath was Bishop of Down and Connor; and in the next century the martyred Cornelius O'Devanny, and the fighting bishop, Herber MacMahon, who also met a martyr's fate.

Statistics (1908): Parishes, 60; secular clergy, 167; regular clergy, 21; churches 114; colleges, 2; monasteries, 5; convents 16; total Catholic population (1901), 156,693; total population of all creeds, 671,266.

O'Laverty, A Historical Account of the Diocese of Down and Connor (Dublin, 1878-95); Reeves, Ecclesiastical Antiquities of Down, Connor and Dromore (Dublin, 1847); Brady, Episcopal Succession (Rome, 1876); Lanigan, Ecclesiastical History of Ireland (Dublin, 1822); Healy, Life and Writings of St. Patrick (Dublin, 1905); Meehan, Irish Hierarchy (Dublin, 1872); Benn, History of Belfast (London, 1877-80); Irish Catholic Directories.

E. A. D'Alton.