The 12th of July is marked in Northern Ireland with marches by the Orange Order, in celebration of the Battle of the Boyne 1690.
The Twelfth of July Parades have often been a source of sectarian conflict during Northern Ireland's troubled past. But in the more peaceful times of today, the marches are becoming less contentious, the hope being that they will take on a more carnival atmosphere for those that take part in them.
To understand the issues surrounding the 12th July Parades, you have to look back into Ireland's troubled history and the Williamite Wars in Ireland during the 17th Century. When King James VII and II of England, Scotland and Ireland (at the time Ireland was a British domain), was deposed in favour of his Protestant son in law William of Orange, the largely Catholic population of Ireland, weren't about to take it lying down.
In support of the Catholic King James, the Irish revolted and set about attacking the garrisons of settlers from Scotland and England, which were mainly centred in the province of Ulster, which is largely present day Northern Ireland. On 1688 the Irish Jacobites (taken from the Latin for James, Jacobus) attempted to take the walled city of Derry. The Siege of Derry lasted for 100 days until the British Navy relieved the town on July 28th 1689.
Skirmishes continued throughout Ireland until the two armies fought their first major battle in the Boyne Valley in Co. Louth, just north of Dublin. The Battle of the Boyne was fought on July 1st 1690 (it's celebration on the 12th is due to the adoption of the Gregorian calendar in 1753) and saw the defeat of the Jacobites, who demoralised, retreated to Limerick, where they fought on until the Treaty of Limerick was signed a year later. James by contrast fled to France and for this desertion his Irish followers referred to James as Seamus an Chaca or ‘James the Shit'.
The Battle of the Boyne, marked the beginning of the end for the Jacobite cause as well as the old native Irish aristocracies and established the future British and Protestant dominance of Ireland. For this reason and as a celebration of their own cultural identity, Unionists and the Protestant Orange Order in Northern Ireland remember the Twelfth of July.