Ulster is one of four provinces in Ireland. Geographically it is in the north of the country and takes in nine counties: Antrim, Armagh, Cavan, Derry, Donegal, Down, Fermanagh, Monaghan and Tyrone. Of these nine counties, six are in the political and administrative unit which since 1921 has formed the state of Northern Ireland.

Before the plantation of Ulster in the early seventeenth century, Ulster was the most Gaelic part of Ireland and had successfully resisted English colonial ambitions. The relationships between Ulster chiefs and those in the rest of Ireland were not close, except when they faced each other across battlefields. Links with Scotland were close; western Scotland and eastern Ulster exchanged immigrants many years before the middle ages.

The dominance of the O'Donnells in Donegal, the MacDonnells in Antrim and the O'Neills in Tyrone gave Ulster some stability and produced military cohesion against Queen Elizabeth I's armies. It took nine years and a blockade to bring the Ulster chiefs to their knees.

There had been earlier plantations throughout Ireland which had succeeded in confiscating land and grafting on a new aristocracy. The Plantation of Ulster in 1609 was comprehensive. The leaders of the Ulster families were forced to flee to Europe and their land confiscated. By 1703, only14% of the land in Ireland remained in the hands of the Catholic Irish, in Ulster the figure was 5%. The Plantation of Ulster attempted to attract not only British gentry but colonists of all classes. The colonists were Protestant and represented a culture alien to Ulster. This policy of comprehensive colonisation was a result of the advice of the Solicitor General to King James I, and was an attempt to replace one entire community with another. The Catholic Irish remained in conditions which emphasised their suppression. They were relegated to a state below servility, because the Planters were not allowed to employ native Irish as servants in the new Plantation towns which they built. The towns were fortresses against the armed resentment of the Irish. In rural Ireland, they were banished from the land they had owned and worked and were settled on inferior, boggy land usually in mountainous regions.

The sum of the Plantation was the introduction of a foreign community which spoke differently, worshipped apart, and represented an alien culture and way of life. The more efficient methods of the new farmers, and the greater availability of capital which allowed the start of cottage industries, served to create further economic differences between Ulster and the rest of Ireland, and between Catholic and Protestant within Ulster. The deep resentment of the native Irish towards the Planters, and the distrustful siege mentality of the Planters towards the Irish, is a crude interpretation of the contemporary Irish problem.

The next two centuries supplied many dates essential to the conflict. The Rising of 1641 against the Planters caused a massacre of Protestants, and the Cromwellian conquest in the 1650s resulted in a massacre of Catholics.

The Battle of the Boyne in 1690 has been sanctified in murals on a hundred gable walls as the victory of the "Prods" over the "Micks" when William of Orange defeated King James II.

The aftermath of William of Orange's victory at the Boyne was much more important than the campaign. It was a mark of the sustained hostility between Planter and Gael that the Penal Laws were enacted by the Irish parliament in Dublin. The laws accentuated the differences between the Irish establishment and its opponents. Having established an exclusively Protestant legislature in 1692, a comprehensive series of coercive acts against Catholics were implemented during the 1690s. Catholics were excluded from the armed forces, the judiciary and the legal profession as well as from parliament; they were forbidden to carry arms or to own a horse worth more than £5.00; Catholic bishops and clergy were banished in 1697; Catholics could not hold long leases on land or buy land from a Protestant; when Catholics made their wills, property had to be divided equally among children, unless the eldest conformed to the Anglican faith; they were forbidden to run schools or to send their children abroad to school. The Penal Laws entrenched the divide between Catholics and Protestants and strengthened Irish Catholicism by adding a political component to it.

During the second half of the eighteenth century relations between the religious communities in Ireland were in a situation of considerable flux. Acting as a counterbalance to tendencies dividing Catholics and Protestants, the coerced and the coercors, was the rivalry between Presbyterians and members of the Church of Ireland. The fact that there were also penal laws against the Presbyterians which excluded them from a share of political power created a Catholic-Presbyterian relationship which was sometimes closer than that between the Protestant sects.

The early success of the Society of United Irishmen in attracting both Presbyterians and Catholics into a revolutionary republican movement during the 1790s appeared to indicate a new Irish cohesion which disregarded religious denominationalism and was determined to establish an independent republic of Ireland. The abortive 1798 rebellion, best known for the Catholic rising in Wexford, also included risings in Antrim and Down. Thirty Presbyterian clergymen were accused of participation, three of them were hanged, seven imprisoned, four exiled or transported and at least five fled the country.

Such a simplistic interpretation of the late eighteenth century ignores the existence of strong community divisions. Secret organisations such as the Defenders and Peep o' Day Boys were formed in rural areas to prevent tenancies from passing into the hands of the other religion. There were persistent and occasional bloody skirmishes waged against each other. A skirmish in County Armagh led to the formation of the Orange Order, which attempted to unite all brands of Protestantism by stressing the common interests of all Protestants.

Early tolerance of Catholics in Belfast was related to their numbers in the city. In 1707, George McCartney, the Sovereign of Belfast, reported "thank God we are not under any great fears here, for... we have not among us seven papists". The industrial expansion of Belfast at the beginning of the nineteenth century attracted large numbers of Catholics to the city. Between 1800 and 1830 the proportion of Catholics in Belfast rose from 10% to 30% and the first signs of serious urban conflict occurred.

The same period saw considerable changes within the Presbyterian church as the liberals were challenged theologically and politically by the hard-liner Henry Cooke who was closely involved with the Orange Order. Cooke and his supporters were victorious. The liberals under Henry Montgomery broke away and formed the Non-subscribing Presbyterian Church. The community divisions began to assume a form similar to one that is well known today.